I can relate to your worries the first night - the first couple of days I kept checking the 'status' screen to check it was still working or the rate had changed when it should.
With regard to practicalities of wearing it, I've tried several ways. I find most of the 'proper' cases/clips too bulky and not suitable for my lightweight work trousers. They either bounce about when I walk, or stick out a mile and are very obvious. I found a small mobile phone case with a swivel clip so I can have the tubing coming from the top, side or the bottom, cost £1 in a discount shop. Although still a bit bulky for my work clothes its OK with jeans. If wearing it on my waistband, I move it to the neckline of my top for loo visits.
Sadly, I don't have the cleavage to hide my pump there in the day, but at night it sits there inside a crop top-type bra and doesn't move. I put a baby sock or scratch mitt on it for comfort.
Best I have found for daytime is a 'Go body pocket' designed for hiding cash etc under clothes. I position it so the pump hides at the side of my natural waist, doesn't move when I walk, no bulge so it's not really visible. Tubing is also out of the way for toilet visits. Wearing this one day, I panicked that I'd left my pump somewhere cos I couldn't feel it bouncing while walking quickly. There it was safe and sound, just so comfy I couldn't feel it. This is how I wore the 'trial' pump while pumping saline and I've come back to it as the most discrete and cost-effective.
None of this practical trial-and-error has put me off. I view it like if I changed my handbag I'd have to find what fitted best where.
It sometimes seems strange not injecting, but I can live with that! As you say, your doses will need tweaking a bit. Also on the pump, you may end up with a totally different pattern from what you needed before. On MDI, I had to change my breakfast ratio as the month progressed, but that doesn't seem to happen now. Used to go quite high after breakfast, now unless I use a square wave, I go hypo 1-2 hours after breakfast. BG only rises about 1-2mmol after eating too which hopefully will be good for my HbA1c.
Try not to worry about the pump stopping. As you say, if you test frequently you'd soon spot there was a problem. Of course you can do an extra test if you don't feel right in any way.
You can probably 'lock' the buttons on the pump in case you lay on them in your sleep - ask your DSN or check the manual to find out how for your pump.
The first few weeks are hard because of the newness of it all. I'm seeing the benefits now - good control and its strange how being connected to a gadget 24/7 feels so liberating