There are three general areas where things can go awry...
1. Unfamiliarity with VP specifically or editing in general
2. Software glitches/bugs
3. Hardware limitations
Most of your queries have been in the first category. Takes time. VP is relatively easy to master vs. high-end editors that exact a steep learning curve (and price).
Software bugs do creep in to the VP quick update cycle, yet most are obscure. Those that can be described clearly and replicated by others are quickly fixed. A user is well advised to stick with a release that works well for them, and not chase the latest update - especially a beta - which may have undiscovered issues. NCH policy is generous: a new release can always be trial tested with few limitations and no watermark. The user's paid version can be reinstalled.
Higher-end hardware isn't necessary, but it helps greatly - especially when dealing with multi-effect/track, lengthy, high-resolution content. A 64-bit release will eventually arrive but today 32-bit Videopad is subject to Windows memory constraints. This can result in issues on complex, lengthy projects.
To succeed, you can try several of the suggestions mentioned in other threads, such as splitting up a longer project, exporting with a different codec or lowering resolution. The best way to get help is to share a project here. Also be certain that a track has not be soloed prior to export.