De-humidifier and Re-modeling

1/ a hole saw in a power drill will cut through cinder block easy.

2/ any silicone will work to seal the hose into the hole.

3/ a little bit trickier. Is access to the sump area easy? if so just put a rubber bung in the end of the pipe. If not, and assuming the room decor will allow it, just make a small solid pipe with plastic or copper and fit a plumbing valve.

just drill your hole using a masonry bit... a hammer drill is a plus..
sleeve the hole w/ a piece of PVC w/ a male or female adapter on the inside...
seal/caulk the sleeve to the block..
use a cord grip to hold the hose and seal the chase while in use...
remove the hose and grip come winter and replace the grip w/ a cap or a plug to seal it up...

the cord grip...
https://www.waytekwire.com/products/1489/Strain-Reliefs/

Dehumidifiers work best when they are located at the floor level, but routing the drain line down hill from the dehumidifier to the sump may require that the dehumidifier be raised up enough for this downhill flow of 1/8-1/4" per foot of run. A small dip of slightly more than the diameter of the hose will act as a trap to keep air from flowing backwards from the sump. If you can't run the drain line sufficiently down hill from the dehumidifier, they make small pumps with float switches, called condensate pumps, which can be placed in the dehumidifier. You could then run the line from this pump uphill as much as 8 feet to reach the drain. I had to do this with all of the condensate from the whole house air conditioner in my last house. I piped it from the center of my basement to the washing machine drain in the corner of the basement.

Charley

Plus one with Everything already said. Cinder block is fairly soft so a masonry bit and standard drill will work if that's what you have to work with. A masonry hole saw will make a smoother hole but you'll need a bit to finish with anyway as the hole saw won't be long enough.

If you have a forced air heating system you could hook it up to a dehumidifier which would eliminate a lot of the noise but of course it would be more costly.