The rule of thumb is that if the hardware is not causing pain or discomfort then leave it in, if it is causing pain and discomfort then, and only then, consider having it removed.
The screws can back out, but that usually shows within the initial 2-3 months.
It takes a full year for soft tissue (tendons & ligaments) to completely heal.
Bone will be basically healed after 3 months, assuming good blood flow (bones without good blood flow, i.e. scaphoid, take 4 months). However, the bone will continue to re-matrix itself for a year in order to find the best structure for the stress in that area.
When screws are removed the marrow fills in the holes within a couple of days but it takes a good 6 weeks to be strong again: and the same rules apply as above. Also, opening the body always introduces the potential for infection. Risk for post-op infection lasts a full year.
You don’t want to re-fracture a bone in the same place that hardware already exists. The damage to the body can be disastrous. However, full activity is possible with proper strength training and body balancing. The normal PT usually isn’t enough to relearn how to use the muscles properly, and to train the body in how to be balanced. Ongoing, longterm strength training is recommended. If you do experience discomfort in the area of the hardware, try to find a real osteopath (one who treats as the medicine was designed): they can work wonders in removing the trauma from the body.
Note: After a pilon fracture of my right ankle, surgeons initially told me that repetitive impact sports were out for me. Fortunately, getting the surgeon onboard to doing the best possible job, the support of good friends, gathering a 100% positive team of sports minded practitioners, as well as tons of stubborn belief and motivation on my part, the doubters have been proven wrong.