First post here - but I've already gotten some great info from all of you. Thanks for your input.

I'm setting up my shop in my basement slowly but surely. I started with a Sawstop (3hp, 52" fence) and got a Delta 1.5hp DC. In the same article in FWW that reviewed this DC as a good one I recalled their saying it was better to run 5" hose to the machine and then reducing to 4" there (if needed) as opposed to 4" at the DC. So I did that - no problem.
Now I have a 20" planer ('99 Woodtek) that has a 5" output and want to tie that into the DC.

The questions:
Notes: I don't want anything permanent/mounted as the basement is a bit small and only the tablesaw will be permanent. I'm using 5" flex duct so far.
1. I haven't located any 5" Y that I would put at the DC to go to my two 5" hoses (tablesaw and planer). Am I not looking in the right place?
2. Both local and on-line sources seem to have plenty of 4" fittings. So are most people just using the 4" and I'm going against the grain with the 5"?
3. I could use the 4" Y that came with the DC and then convert right back up to 5" at the DC but would I still benefit from the 5" duct going to the machines?
4. Are there any recommendations on quick-connect options? The planer will be on a mobile base so I'll hopefully be disconnecting it at the DC when not in use.

Thanks in advance for the advice