with a 4 year old tank, I would look at possibly stirring up the sand bed a touch to release any
nitrate traps you may have in there. I'll spare you the check phos / trate speil but I will ask when the last time you changed your
RO filter was, or if your getting your water at
LFS, when was the last time they serviced the filter there? Maybe test some change / top off before adding to get an idea there.
As far as removal get some plastic tweezers from a cheap johnson and johnson med kit, trust me on this... the black plastic tweezers are a godsend. If you have to go with metal get the type with flat ends (not the tapered sharp ends as they slip off the alga). Use a syringe with the hard to reach bubbles to suck out the guts and then pick off the skins, sometimes it's best to wait on those till they get a large enough size that you can rock them back and forth to loosen them and pick them off, whatever you do try not to pop them. If your not opposed look for some emerald (mythrax) crabs as they will help... but some dont want the species in their tanks. with the hair algae it's a toss up, if its angel hair (fine) you can hit it with a lawnmower blenny with some luck... if it's briopsis (feathery) your pretty much manually removing it.
I have a method I'd recommend but I'm still testing it and I'm certain it's probably not the best way so I'll refrain here, it utilizes a toothbrush and a peice of airline tubing.... (insert imagination here).
Good luck!