It seems like the currency fields should do math. This is a nice feature that many unrelated softwares have, where you can tell the field 1+1, tab off and the field updates to 2. It makes it a lot faster for putting gold amounts in on the fly and would be convenient. Is this something that is getting updated when the new Character Sheet comes out? 

Agreed!!! 

One should be able to add the amount of gold one find... 

Also there should be an option for buying stuff when adding items E.g. that D&D Beyond subtract the gold automatically (if you so choose)...

Agreed! Like a standard gp cost on the item that you can adjust on the fly and press "buy". I think same could go for selling too. At the very very least though the currency fields really need to be calculated fields. 

Second, Third, and Fourth this idea. We know it can be done because of the hit points, but simple things like ammo, thrown weapons, and gold, do not have this feature.