SMaSH OG and hops

I would like to start doing some small experimental batches to get a taste for different ingredients, and also while I am at it build up my yeast for my bigger batches. I want to start with some SMaSHes to compare different base grains. What I am wondering is what is a good OG to shoot for? I want it to be low enough to not stress the yeast too much, but not so low that I can't taste the differences between grains. I plan to do a basic pale ale malt, Marris Otter, Golden Promise, Vienna, and Munich.

Also what type and amount of hops would you suggest, and what schedule? Should be just enough to get a good taste/aroma but not so much that it over-powers the malt. I know vitually nothing about hops, as I've mostly made malty english beers up until now and have mostly ignored the hops side of the equation, but am planning to branch out into american styles too.

I am thinking these will be 2.5 gallon batches by the way. (Then pitch the yeast into 10 gallons using trusted recipes)

Thanks

I'm a novice in home brewing and have never done a SMaSH beer before but a guy at my home brew club brought in a Maris Otter/Nelson Sauvin SMaSH that was fantastic combination!

I'm heading to the store later today. Think I might go with 5 lbs grain. It will be my first BIAB so I'm not sure what my efficiency will be, but it should put me around 1.055 or so right? That shouldn't stress out my yeast too much right? Still not sure how much hops I will need though.