For the platforms: Are you able to obtain MDF plywood and livestock stall mat where you are? If so, I would guess you could build yourself a platform for cheaper than the ones you're looking at. Wood glue and screws will be enough to assemble these into a platform. Two layers of 3/4" thick plywood (or better yet, three), with one layer of 3/4" stall mat on top is enough. If you're planning to have the space, then a full 8' x 8' platform is a good size to accommodate a rack and a bench, with room for deadlifts and power cleans/snatches.
Bolting down your rack is a safety issue. It doesn't need to bolt into the floor, however, but the platform on which you're lifting. If you build your own platform, this is easy enough - you use a large enough screw to fit into a bracket attached to the rack, and long enough to penetrate your mat and most, but not all of the plywood. You do not want the rack changing position or falling over.
I am curious why you're selling yourself so short on how much you can get your weights up to.