Q&A for How to Caulk Shower Enclosures

Use the hairdryer with a low setting to melt the caulk. Then scrape it off with a razor blade. Keep in mind that this can only work when the silicone caulk isn't between pieces of plastic, or it will cause damage.

Using a caulk removal tool is advantageous because it works with acrylic, latex, and silicone.

Yes, that's why you would caulk your weep-holes, not the door itself.

No, that's likely not nearly enough. You'll need to caulk any and all visible cracks, including on the ceiling. All moisture and humidity should be handled only by the plumbing and exhaust fan.

Pure silicone caulk will not stick to old, dried caulk. The latex and acrylic stuff might give some stick, but don't rely on it, especially around an area that is guaranteed to get a lot of water exposure. Remove all the old caulk first, then get a foam backer that fills most of the gap (also called backer rod, or backer rope, you can get it at the big box stores) and use that to fill the gap. Then, caulk over that with a high quality silicone. That should give the best results.

It actually sounds like you have a construction flaw where water is getting behind the tile and you've caulked unknowingly to a moist surface. Re-build to correct it and your caulking.

It's your choice. As long as the caulk is bath and tub purposed, you'll get the same results and longevity. (I much prefer the acrylic though.)