1) Weak heroes! At Rohan one of the weakest heroes in fashion. Therefore I suggest to add constant or draft Helm's hero molotoruky.
Their heroes are not weak, they synergize extremely well with eachother, and if you Banish them they are a deadly force, each of them having the damage of a hero killer.
2) To remove from the book of spells ability for 10 points camp!. I will just sharpen that it is duplicated with camp from the Outpost!
This is a terrible idea, the 10 point power of Rohan is one of the strongest in the game. It gives you unlimited, elite cavalry, fully upgraded who can switch to bows, for FREE. Putting this on an outpost would be unbelivably broken.
3) To increase defensive abilities of the camp / Outpost.
If you mean the Exile Camp, it is not meant to defend itself. It gives an amazing leadership, you should be using troops to defend it.
4) As the option can be added and the Outpost Vestfold
If you mean to add a Westfold Outpost for Rohan, you should post it under the Rohan Outpost Suggestions board. Also, I believe something along those lines was already suggested and rejected some time back.
5) To change couple of abilities from the book of a spell (for example it is possible to add Gandalf as the draft hero instead of Galadrim with Haldir.)
Since Gandalf is your only proposal here, I disagree with it because Haldir fits nicely into the faction. If you have any other spell replacement ideas I'm interested in hearing them.
6) To add pedestrian elite! It so is not enough for it.
I don't understand this.
7) To slightly change abilities of heroes especially of Theoden and Eumer
Theoden already has one of the best ability rosters in the game, the problem isn't his abilities, its his health and how long it takes to level him up. As for Eomer, I will agree that his ability set is lacking, but I don't know what abilities could make it better. Have you any ideas?
8) To add horse group with copies (are strong against spearmen and monsters)
I would support this with the goal of making Rohan a cavalry faction, the problem is that then there would be no counter to Rohan. Having a unit that is strong against its counter is incredibly difficult, if not impossible, to balance.
9) To add to elite group a feature to exchange astride a horse / or pedestrian group
I think having an entire tier of troops who can mount and dismount would be really broken, as you can trample the enemy, dismount to fight, or quickly remount to trample again. This wouldn't work.
Thank you for your attention ! I hope these ideas (or at least used part) you like!
Thanks for your post, but I would suggest putting more thought into your ideas and presenting reasoning why the faction should have your changes next time. Also, if possible, try to improve your English a little bit
Welcome to the forums!