Hi Pat, sorry I didn't notice this post beforehand. I too had similar issues to begin with (particuarly the fear of losing the small parts). What I did after my first two kegs was to muck around with all the parts, putting the hose as far into the elbow connectors as it would go, so I would recognise the click that signalled that was where it meant to go. I also mucked around with fitting the connector onto the tap and feeling the connecting click. The connecting click is the second click not the first when you are connecting to the tube, the tap, the filling cap.
I also wasted a keg liner practicing non stop until I got screwing the cap onto it. All up I probably spent between 30-60 mins doing that but it meant that when I was kegging, I was confident in that part, so I wasn't worrying about every part of the process.
To minimise my fears about losing small parts, I made it a bit of a ritual when it came to kegging. This meant that I was doing the same thing in the same way each time. I would lay out a towel on the kitchen bench ( preferably not one you've just dried yourself with :)) then disassemble every part, taking time to spray them with sanatiser. I would let them dry and then I would put the small parts back into the caps and construct those parts. Then I would connect the cap to the keg liner and check it was on even, then I would connect the hose to the elbow joints and finally the filling cap.
That part of it is really hard for me because at the best of times I have the attention span of Homer Simpson, so being that structured was an effort...and to a point, I really didn't enjoy kegging because I had to observe structure and adhere to it but you know, pay off in 6-8 weeks with delicious cheap beer.
I understand what you say about spending a fair chunk of coin putting this system in place ( I did too) but given you have, it would be remiss of you not to do some practicing outside of actual kegging, do some trial runs so when the time comes, you can feel a little more relaxed about the process and have a solid method that will bring you some satisfaction that has no beer on the floor ( which is worth crying over) and it all inside the liner.