Can I apply for both a certificate of residence and submit my 90-day report at the same counter in Chaeng Wattana?

It's partially correct.

At the Chaeng Wattana office in Bangkok,

IF you have an online appointment for a 90-day report, yes, those are done at the same counter, B.

IF you want to do a 90-day report as a walk-in, no, those are different. 90-day reports are handled at Counter A while a "Letter residence information in Thailand", or so-called residence certificate, is at Counter B.

You will need an updated TM.30 with a check-out date for R/C. This means TM.30 receipt with "0 night" may not work.

You need a filled application form for the letter (available at the immigration office) and, a passport-size photo, other than the passport and its copies. And 200 baht cash for postal related fee.

Better to bring the rental agreement and the latest 90-day report receipt just in case.

A letter will be sent to the address on TM.30 in 1-2 weeks by EMS.

Unfortunately, details about the residence certificate are out of the scope of this group. Sorry. (Usually, we reject posts about Residence certificates)