So I have a Miyata 712 from '88 and it has a period Shimano 105 groupset, albeit modified with a straight handlebar and a SIS shifter for the rear.
Also, the cassette is a 7-speed one instead of the original 6. Chainrings are original Shimano Biopace.

The rear dropout spacing is 126 mm.

Switching back to drop handlebars now.

So I have odered a set of Shimano's new 2x7-speed brifters (A070 to be exact) and I'm wondering if a full set of A070 parts would be a good choice.
The 'Tourney' A070 is an entry-level groupset of course, but I would think it should still work better than a 25-year-old 105 set? The current system seems to
require constant setting-up.

Are there any other gearing options to be used with these A070 brifters? 2x7 -speed sets are rare these days, it seems.

Can I use more than 7 rear gears with the 126 mm rear spacing anyway?
...as for bending the frame to 130mm, would that mean all modern groupsets would fit straight on? But isn't it risky to bend the frame?

Assuming I can stay at 126mm and just use the 7-speed cassettes, what would be my options to switch to modern wheels on this bike?
Will the rear spacing affect wheel choices?