I am adding a string (5-6) of receptacles to an existing 20A circuit in my basement that currently has just one 15A duplex receptacle on it (with 12/2 Romex). I am planning to replace the existing receptacle with a GFCI and install other receptacles downstream (with 12/2 Romex) from the Load side of the GFCI.
Should I use a 20A GFCI?
Is there any reason not to use 20A receptacles (apart from the cost vs. 15A)? Any reason not to install a single 20A receptacle (for a future air compressor or something), and the rest 15A?
The other circuits running outlets in my house are 20A and use 15A receptacles.