Go on a parts fische, and compare no's. Or, find the shaft you're looking for on fische, and hit part no, then 'where used'. That'll give you a list of engines that use that shaft.
Nope. Turn the carbs on their side, float pivot uppermost. Angle carbs until float platform barely touching spring loaded peg. Measure from gasket face to top of float. Awkward, but not impossible.
Carefully!!!
Take the end nozzle off, thread the gun into the caliper carefully. It's a different thread, but it'll go in far enough for what you want to do.
If you can't get them out, squirt a bit of something like Waxoyl in the hole before fitting a new nut. Hopefully, it'll clag all the loose bits together at the frames low point.