Importing bacteria from the other tanks
Yes, the water from the biowheel will help, if is is nasty and ugly and brown that is best. If it is clean and clear then you need to take the cartridge from his system and swish it in a bucket of dechlorinated water, mind the temp.
The more dirt the better. Pour that into your filter, upstream of the pads so the pads catch all that mess.
With pH above 7 you probably have a good KH. If the pH begins to fall, you may have a problem. I'd worry if it got to 6.5 or less from your starting point.
Call your water company and ask for the General hardness, Carbonate hardness, nitrate, nitrite, calcium, magnesium, conductivity results -- they will mail you a statement with all these values, plus some more that they test. Put it in a file to refer to once in a while. There is another one that tests chlorine and ammonia and ecoli bacteria and some other things that are important, but you want both forms.