Pump won't work at pool opening

I have an Anthony 16,000 concrete pool built in 1980 and renovated in 2004. Hayward pump Model C48L2N134B1 installed in 2004. I opened the pool yesterday and the pump won't work - just makes a loud hum/screech noise. I reached into the impeller and can't feel any movement. I called Leslie's for service and no one can come out until June 4th. I will try other service companies today, but I'm sure everyone is booked up at this time of year.

In the meantime, how can I keep my pool from becoming a swamp? I put in my sump pump and will run that while sunlight is on the pool. I have a backflush hose on the pump. Would it be better to leave the hose on or take it off for the most circulation? Leslie's suggested I use only chlorine and no other chemicals, but my PH is high (I use liquid chlorine as directed by Pool School) so I don't know whether to use dry/muriatic acid first or if the circulation would be too poor and this would damage the pool. Would brushing the pool after adding chemicals be enough for circulating? Would algaecide help at all? Also, what level should I keep the chlorine?

I don't like to replace things I already have; would rather run them until they can't run anymore, but since the pump is 10 years old, is it smarter to replace than repair?

Sorry for so many questions, but I'm in a bit of a panic. I've never had a green pool before and I'm hoping to prevent it.

CH 0
PH 8+
TA 90
CH 210
CYA -30 (Went to 30, but could still see dot) Have been fighting high CYA for last two years not anxious to add more.