Visibility depends on a lot of things. You could paint it all DayGlo colors, as I did one of my bikes (and will someday do to all of them if I ever get money for that), and/or use a flag (optionally with lights up the pole), as I've seen on a fair number of recumbents around here.
Lighting it like a regular road vehicle will help, too, since you will also be using the same communications system that all drivers understand (many don't appear to know what hand signals are, even if they notice them, and that includes law enforcement!). Turn signals, brake lights, marker lights, taillights, headlights, etc, would all increase your visibility even in daytime, if you have ones that are of comparable brightness to other road vehicles (as I do).
Dress in bright clothes, as well, with a brightly colored helmet (or bandanna or hat should you not like helmets). Safety vests like crossing guards and construction workers wear will also help.
As to it's suitability for motorization, all I can see right now from the tiny image is that it appears to be an aluminum frame with very simple frontwheel pedal drive. It looks like it also has plastic wheels, which while lightweight might not be as strong as regular spoked wheels, depending on what they're made of.
The rear wheels appear to be like wheelchairs usually are, just free-wheeling on bearings. It's possible they're actually driven from the front pedals, but I can't see that from the image.
If you get a hub motor that has a stub-axle shaft, you could put a pair of them on the rear wheels, and even use two independent controllers, so you could steer with independent throttles.
It would certainly be interesting to ride that way.
Alternately, if the rear axle attaches to both wheels and spins with them, rather than being just a support for bearings in the wheel hubs themselves, you could use a single motor driving that rear axle, either directly or via various reduction schemes.
The frame looks too light to support lead for any decent range, if it is actually the aluminum it looks to be, so you'd probably want NiMH or LiFePO4.
If it is just a coaster brake, you'd probably want to add some other braking method. If you don't use a freewheel on the motor(s), you can use regen braking and then there are no worries about whether it'd stop you.
Otherwise you could add some frame brackets for either disc or rim brakes--you'd probably have to replace the wheels in either of those cases, though.
