be careful of generalization and anachronism. There is no one-size-fits all definition. For example, many generals employed aides of a range of rank. There was a huge difference in how a colonel could be employed and how a lieutenant could be employed. There were also differences between countries and between individual generals.
Aides were generally selected for having real soldiering skills and a lively intelligence. They were exepcted to thoroughly understand the administration of the type of unit under command and the how information was to be collated at their level of command. In other words, most aides were experienced officers.
Some generals took on a certain number of aides as a favour to friends or benefactors. These young men often lacked experience and were of questionable use other than whatever pride and determination they might possess. At times a general might take on an aide as a form of ward - the young son of an old friend. A number of memoires speak to that. At other times it was a means of trading influence. You'll find the sons of many prominent French generals pooping up as aides de camp, en route to early promotions, if they showed any promise.
There was a huge amount of work to be done in a command of any size (including administration, recconnaisance, inspections and message carrying). Accordingly, generals tended to pick aides that would actually be of some use, and in larger staffs had a range of ranks and talents. At one extreme, you have Napoleon with a huge retinue including the most junior ranking officers up to senior generals fit to take over command of a corps or other tactical grouping as required. At the other end you have brigade commanders in all armies who were entitled to one or two aides and staff personnel. These individuals were selected for knowledge, experience and aptitude - not dancing skills or knowing how to find a chef. Consider the duties of the Brigade Major in the British army. There's a fair bit of material available on line to explain the functions of this key staff officer. For Napoleon's staff, you should obtain a copy of "By Command of the Emperor". For a remarkably good read about the duties of a general's staff, find a copy of "The Proud Canaries". This is a novel, but written by David Johnson who has written two books on the French cavalry. The story focuses on an aide to General Lasalle and gives tremendous insight into what was done on his staff, the range of duties, and how those duties were parcelled out across ranks. It is also a very fun read. If you are still working on a historical novel, this is a very good example of one for the period. Johnson's novel is about the one particular general in the French army, but much of what he writes about can be generalized to all armies in terms of the work that had to be done.
I have to admit that I didn't like your definition at all. Here's my breakdown of major issues I have with it:
"An Aide-de-Camp was a Generalís personal aide " - OK, but it connotes personal service. Aides worked as staff officers (and I am presuming you have little idea yet about how much work that entailed), couriers and took on assigments as order. These assignments might range from leading a patrol to auditing records in a unit to liaising with other commands.
"who did all required in his generalís name" - Not quite. To do something in person's name means that you can speak on behalf of that person and make decisions. This might have been true of some aides (think of Colonel Gordon on behalf of Wellington or one of Napoleon's General Aides-de-Camp. Some wet nosed lieutenant would NOT be able to act in a general's name.
"including secretarial duties, communications and finding the best chef and even substituting for the generalís presence at a local ball if necessary." - What a hodge-podge of duties! Think about the range of ranks on many staffs and consider if any aide could be a stand in for the general? It is also bizarre to me to see "finding a chef" placed on the same plane as administration. While some dilletante might consider that to be important, ask how long such an individual would last under Wellington.
"An ADC was considered a trusted member of a generalís military Ďfamilyí" - I think you have borrowed this phrase from somewhere, but cannot place it at this moment. It is OK as far as it goes. If a general found he couldn't trust an aide he was obliged to either dump him or give him only trivial duties if politics forbade dumping him. Calling any general's immediate circle a family is a huge stretch.
"and his statements or commands were to be taken with the same level of seriousness as those of the ADCís generalís" - No, most emphatically so, in almost all cases. Whatever he conveyed from his general were the statements or commands of the general. Anything the aide said on his own hook could NEVER constitute an order. There are plenty of cases where an aide arrived on site, found circumstances to be not as envisaged by his general, and consulted with the local commander on the best course of action. There were other occasions where an aide had to extemporize on site. It was also common for a local commander to request the opinion of a senior aide-de-camp. In this way the local commander could gain some insight as to whether his course of action would suit the higher commander.
"Social skills, including translation, were considered desirable skills for an ADC to have and hone." - Since when is translation a social skill? Imagine being dropped into Portugal and being expected to find a route and forage on the route. Damned hard to do without some form of translation or common language, and most certainly nothing social about it. This sentence gives the impression that you think an aide's job was about dancing and eating cucumber sandwiches. There may have been a certain requirement for that at higher levels where that general was obliged to host various social events. It sure doesn't apply to most aides for most generals (other than the usefulness of speaking multiple languages).
Another book worth reading is Marbot's memoires. He was aide to several marshals. You have to winnow hyperbole from fact, but there are some very useful details in this much maligned memoire. For a General Aide-de-Camp to Napoleon there are also Rapp's and Savary's memoires.
I hope this gives you some more context. Keep asking questions - you have set a very difficult task for yourself with this novel. Regards,