Slitherine

Is there a good list for 800-900 pts out there for the Austrian in Germany army in E&E that someone would care to share?

Also, If I choose the Russian ally option, can I just have cuirassier in a division, or do I still have to add an artillery unit too?

Unfortunately I have never tried that particular list, but it looks like you have to take the horse artillery for the Russian cavalry.
I have had luck with the army of the lower Rhine 1796-97 on page 33.

Quick look at your list I would suggest taking the Light Infantry and Jaegers, they can form Tactical or skirmish if you wish. The Tyerolean Jaegers are pretty expensive and can only skirmish so hard to keep in the fight and they can't do much other than shooting. Fei Corps are cheap but permanent skirmishers so not good for much once you have to close with the bayonet, Grenzers average Irregular are pretty good in any army I have used but I still prefer the poor Drilled version (not in this list though) over Conscript as they can still shoot as poor and they can form tactical so can stand up to horse if need be. Perma skirmishing troops are a bit harder to find a use for once it gets up close and personal, in my experience.

Load up on arty, put cav attachments with your units if you can and keep your divisions small, command is a real problem for these early armies as there is a lack of Brigadiers to help out. I prefer to put Brigadiers with a cav unit so they can operate independently, keep in mind you only can have 2 for the whole army and max of 1 per division.

Hope that helps a bit at least.

If you choose the Cavalry division from the Russian list:
The horse artillery are not compulsory - 1/3 of their minimum is less than 'half a unit', therefore they need not be taken.
Since there is no minimum their maximum is halved, so you are permitted to take up to 1 base as an artillery attachment to one of your cavalry units.