Do you know your tap water parameters, ph and nitrates in particular? If they are 0 and 7.0 ish, then this will make life easier in the tank.
I agree with above comments on the pleco's..if they are common or sailfin, or any or the larger ones then you should change them eventually. Obviously, if they are still small, then you have some time to consider your options - they arnt going to fill the tank overnight

If they are for clean up, try bristlenose plecos (excellent algae eaters!), if your not interested in breeding them, get 2-3 female ones, or if you do fancy some baby bnose, 1 male 2 females, but make sure you have a selection of caves to keep him happy.
A lot of the smaller sized pleco's can be expensive, and some of them don't actually eat much algae. i suggest you do some research on the smaller cats - this
thread would make a good starting point
The only other point, you may have to keep an eye on your angels, due to pairing up, defending an area etc etc.. if 1 or some of the angels start to take a beating, then it(they) would be better being rehomed, but chances are, this scenario will be a long while off yet.
On adding the yoyo's...might be better if you added more of the same kind of loaches you already have, they enjoy company of their own kind, and chances are you will see them more as a pack.
Other than that, if your maintenance is kept regular and routine, then it should be plain sailing - assuming your tap nitrate is low!