Even if you use CO2 I think you should keep a small pump to check for unseen punctures in the old tube, and also to get enough air into the tube to make sure the tire is seated before you blast it with CO2. I don’t know if you’ve ever seen a tire throw a bead while inflating with co2, but it isn’t pretty.

I love the Silca Impero (https://silca.cc/collections/mobile-inflation/products/impero-ultimate-frame-pump?variant=1749950788), its expensive but they are built to last.

The best advice is to just do it. You don’t need to overthink it, really.

It could have, if you have a bubble level put a clipboard on the saddle and then the level on that and see if its level.. If its nose up drop the nose to level it out. If it is level or nose down then look into a saddle that is harder with much less padding.

Have you changed cleats since your fit? If so, did you mark the position of the cleat to put the new one on in exactly the same spot?

Without seeing you on the bike its kind of hard, but if its your toes, I’d say move the position back.

Make sure your saddle is level and not nose up (unless that saddle is designed to be such, like the specialized “cup”), and don’t go nose down or you will end up with numb hands. I recommend perfectly level +/- 2 degrees, use a clipboard to cover the entire saddle and take your measurement off of that.

It is most likely cleat position, if they aren’t setup right hotspots and numbness will occur frequently.

In your situation it sounds like it could be shoe size, but it could also be cleat position. If the cleat is setup incorrectly you can have hotspots or numbness, and loosening the shoe could allow the foot to move just enough to change the cleats relative position and avoid the pain.

You could be on a saddle that is too wide or too narrow for you. You want your sitbones to be situated on the saddle where the padding is focused and where the shell is designed to hold you, so that they can support you correctly. Too narrow and you sit on the soft tissue and too wide and you sit towards the center…

Go to a shop with a saddle measuring device and find a saddle that fits your sitbone width. It can also come from a saddle that has too much soft padding causing you to sink in and put pressure on nerves that end up going numb; Look for a saddle that is stiffer with less padding.