Glad you got the gamepad working.
Ramps can have pictures mapped to them yes, just no transparency.
How do we get the graphics? Any way we can. Some are scans, some are photographs, some are drawn, some are given, some are stolen, and some are a mix of those and other ways. The biggest source of pictures, you have found it, it's the 'net.
Actually the best way to learn is to just jump in. Look for an original that you like, and play it. Then look at the script. There is really a lot less programming needed than you think to script a complete game. The real answer to the programming techniques absolutely needed to program all the elements of a pinball table is much closer to 8 than it is to 8,000,000 or even 800.
Nobody I think, that has felt inclined to make a pinball game in VP has ever abandoned that effort due to not getting the help they need from this community and it's various forums. Quite the opposite is true, this community has guided many unique table builders to produce many unique pinball tables. A few authors have built templates, that are tables that have the redundant and basic structure of the workings built in. With those it's more dressing them up and laying them out than it is programming.
You said you have some unique ideas. For many that would be the biggest stumbling block. It takes no programming at all to shape walls, put elements onto your table, and paste graphics. It takes very little to create sound events and score tracking.
Start by shaping the main wall and making walls for guides and lanes and drop in some standard bumpers, lights, and things. It will be more playable than you may think as is. Bumpers and slings for example don't need any scripting to function, only for sound, scoring, and grouping, etc.
Have fun.