Questions about the mechanics of custom races

Hi, I hope somebody could explain how to do any or all of these things in a custom AD&D 2e Race:

- Change base Movement Speed
- Add Ability Score modifier
- Add special movement option (e.g. Swimming Speed)
- Racial Weapons (E.G. claws - which aren't equipped but are always available in Actions)

I'd understand if the last one wasn't possible, but the other ones are done in the PHB races - yet there is seemingly no field to do it myself.

Thanks!