Ok problem 1 I have no idea what you are talking about. Is it part of the ‘kips’?
Re the carb the float needle & jet can leak, on an 88 not sure but think you have a Mikuni carb so new float jets would be easy to get. But first thing is pull the float jet out, replace the o-ring. Drop a ball bearing down the hole & give it a decent tap with a punch to make sure it’s even & check the float jet. If it is really badly ridged a new one is easy to get or 2nd hand same size.
Also the fuel tap should be turned off, if it still leaks (in off position with hoe pulled off) an aftermarket rebuild kit is cheap & easy to fit.
Still in the dark about your oil leak & where you are talking about but as far as running rich do make sure the air filter is not past it’s best. On these old carbs you should look at the needle jet (as the needle passes through) as these do wear oval, & the needle itself - happened to a friend of mine & was much improved when he replaced it.
Ahh, was that what you were talking about when you said needle seat? I assumed you meant float seat.