I have added 4 foot cones to my current raft. 2 in the front, and 2 in the center compartment of a 2 thwart raft for the "third row" of paddlers. The second row and last row (including guide) all use the thwarts for foot holds. This is for a paddle raft setup with as many as 8 paddlers. A foot cone for the guide position is unnecessary in my opinion.
Angled out as mentioned. I'd attach them just like any patch that you want bombproof. Prep is everything. Roughing up, cleaning, etc. The glue accelerant makes a stronger hold as well. Trace the footprint of the patch onto the floor of the raft. That way you can be more precise when brushing on glue. It's the glue overlap that makes for an ugly patch job. Of course roll out the patch to get the air out to get full patch contact.