Welcome aboard!
I do not think it matters what size army you have. You can play the size game for the points you have. You can play regular battles as far as I know, the special scenarios may give bonus points or might be played out at local stores. Similar to SoC type stuff so they can write some of their own fluff.
The campaign site opens up on the 16th I believe, so we'll find out more for sure then. Unless it's already stated in a WD, which I do not purchase.
If you want, Talvisielu, please register in recruitment if you have not already done so. That way we know you're on the roster.
Again, welcome aboard and we look forward to fighting along side you in the coming campaign!