Worried I wont be able to get the grain all in the strainer if the water is lower?
IMO a strainer basket is very optional...I have one yet have never used it FWIW.
I have 20 gallon pots, and they are big!!! Like 18 X 18 inches...while it will sure work for a five gallon batch...the huge size will make a bit of an inconvenience for only a fiver batch IMHO.
Could someone reccomend a good thermometer with a probe?
FWIW I like the simple digital stick thermometers, since you can move it around the mash and check several spots quickly...big box stores have them for like ten bucks and I have found them to be pretty accurate...get one as a spare if nothing else.