Here are a couple of extracts from the Zhmodikov's book on Russian tactics of the period:
For the period 1805-1807 this quote is offered:
'As it can be seen, the Russian cavalry was much too impetuous, often became overexcited in pursuit, and sometimes attacked without orders; there were some problems in cooperation between regiments and also, probably, in the use of reserves. The reasons for all these problems werre the lack of proper organization and training above the regimental level, and inexperience.'
This quotation is from a letter written by AI Mikhailovskii-Danilevskii to the Tsar in 1815:
'I don't like our way of using cavalry. We would send a squadron or two, a regiment at most, to attack [an enemy], and usually without any purpose. By such [uncoordinated] attacks, we would either manage to disorder the enemy a bit, who would quickly rally, or we would be, ourselves, overthrown, and having retreated, we would rally. On the contrary, I absolutely agree with the French. They concentrate all their cavalry at one point, and don't rush at the enemy at full gallop, as we do, but ride at a trot, slowly and in good order, and, chargin at once with all their force, throw the line of enemy troops into full disorder, and disrupt all their plans. I discussed this with Wellington several times, and he holds the same opinion. He wrote that, in no battle, the English cavalry, perfect in many respects, produced such an effect as poor French cavalry, which consisted of bad horses and of men who are poor riders.'
These are only two 'snapshots' from a two volume work that I would highly recommend. Hopefully, these will partially answer your questions.
It should also be noted that the Russians employed 13,000 cavalry very well in 1814 at La Fere Champenoise in a victorious engagement.