Turn signal flasher

[Squishman]

I ordered 4 turn signals and a handlebar switch. Also a horn. Here are the parts I ordered:
https://www.ebay.com/itm/383696350702?autorefresh=true
https://www.ebay.com/itm/404473886535
https://www.ebay.com/itm/394127233842
Can someone tell me what is the proper flasher and do I need one or two?
And also, do I need a horn relay?
tia.