How much expansion space is need for solid oak flooring?
3/4" gap all around has been the norm that I have seen on old house installs. If the drywall is high enough to make that gap to the framing all the better. That way the gap could be bigger and the base will still cover if you choose to not have shoe mold as many new installs nowadays go that way.

The biggest issue for solid wood floors over a large area is getting the wood acclimated. This usually means leaving the flooring in the environment in which it will be laid for 2 weeks. In the get it done now mentality of today, that never happens. then it is a matter of making sure the wood is within an acceptable range of moisture content that is compatible with the subfloor. If you can get or have a moisture meter, that will tell you what you need.

If you are coming out of a heating season, you home will be really dry, somewhere as low as 2-4% Moisture content (MC) Material as it comes from the suppliers, as long as it has not set in a warehouse for a long time, is supposed to be about 6% MC. This is not a bad difference. Usually if the floor is within 2% of the subfloor, there will be no issue. During the summertime the humidity will increase the MC to perhaps as much as 10%. Still the wood flooring needs to match this closely or it will try to swell rapidly to match the MC of the subfloor. Buckling may occur.

If it all goes in at the same MC or close it will all move together and have minimal issue. If the wood does swell up too much, that is what the gap on the long edges are all about, insurance. The ends to not need the same concern, then length of the floor only changes ever so slightly as the MC changes. In my experience ther has been no other need to make any other accomodation for expansion than the gap at the walls, no "T" strips needed.