A shower head is a tool found in the comfort rooms where the water comes out through spraying. There are various types of shower heads. You can try Grohe 28 897 000 Relexa Ultra 5 Spray Patterns Hand...
Aerator in shower head is plugged up. Unscrew head, clean it out, and replace. Make sure you have teflon tape on hand for the treads on the shower arm when putting the head back on.
Yes, you can install a tee in the riser. The pressure loss will be minimal since both shower heads will have a flow restrictor unless you remove them. If you remove them, you probably wont notice any...