There is some useful info in our wiki, maybe you can find some relevant data in there:
Brand and Model Compatibility Chart - E-Cigarette Wiki
But as for your other requirements, you would need to to find what you need by a process of elimination, perhaps by asking specific questions on the forum.
For example 48-hour battery life in use is a tough call, you'd be looking at a 3.7 volt mod with the largest possible battery. Check out the modders for that. If you mean 48 hours with occasional use, then many mods would suit. Under a normal / heavy use regime, mod
batteries commonly last 6 to 10 hours, as against say 2 hours for a standard 510. To get one in purple you'd need a custom spray finish, as available on a Chuck for example. Mods aren't cheap though, because you are paying for big
batteries and custom build.
You will probably find that you just can't get everything you want in one
device, so you need to prioritise. Or get a modder to oblige, for plenty $$.
Don't buy a mod without these safety features:
www.e-cigarette-forum.com/forum/announcements-rules/77710-basic-safety-specification-mods.html