FWIW, I own and use a range of Leicas from the oldest (a 1926 one) to a fairly modern digital (the M9) and have dozens of bodies and lenses. After reading this thread I think a little clearing up is needed.
The OP is asking about using two lenses from the 1930's on the M2 but hasn't bought the M2 yet; not that it matters as the differences between the M2 versions are all on the left hand side of the front of the camera.
The first point to make is that there are dozens of different adapters and they vary a bit but all do the same thing. Meaning that the screw threaded lens screws into the front and the lens then has the correct bayonet fitting for the M2 and brings up the correct frame-lines. And that is all there is to it because the original question was about two pre-war lenses on the M2.
So two adapters are needed, one to bring up the 35mm frame and the other to bring up the 50mm frame in the viewfinder.
It's best to know a little more before you buy; the adapters have two notches on the lens flange; one on the flat of the flange and at the back of it to engage with the lens release button's catch and the other cut into the side of the flange and often coloured red to line up the adapter with the camera when putting the lens on the body.
You should also know that many people adapt the adapters with a file and so you can buy them labelled wrongly. Given the prices charged for genuine & fake old Leica adapters that is disgraceful.
In use you also need an elderly Leica made rear lens cap; the black plastic ones with the grey plastic inserts*. They have three lugs on them that fit the adapters and act like a peg spanner and make removing the adapter very easy. (Alternatively buy a swear box and some sticky plasters as the adapters can be painful to remove and sharp; a thick leather glove is also useful.)
BTW, my 3,5cm f/3,5 Elmar uses cheap old anonymous adapters and likes them and the same goes for the Summar. But, a big but btw, I bought them from a dealer I knew and so they were OK.
I don't think you should worry about the infinity lock on these two lenses and the M2.
I'll try and find the time to take a few pictures and put them on my smugmug site sometime.
* The grey plastic often get damaged by the bayonet and so check carefully. Good ones take the bayonet and it turns and stops; failures turn forever and the cap can fall off. Either work OK as a peg spanner.