I’ll get a release post out this afternoon once I get through some more Support tickets, I did it quietly so that I’d have time to work with early release users last week as well as to prepare documentation and a decent release post. To answer your queries:
1. Yes it is a separate Plugin and since PID and SID share the same AJAX import engine they don’t work well when activated alongside each other, on activation SID will de-activate PID.
2. The Plugin you made for PID *may* work, I intend to keep as many WordPress Filters from PID intact as SID will some day replace PID, both Plugins will be actively developed as PID right now has much more Product import capabilities than SID.
3. SID is a very early release but it is better in the hands of users than gathering dust on the shelf. Customers are buying PID for Product imports and get SID complimentary while the functionality is being built up. When SID is able to stand par for par against PID then I will deprecate PID but as above both will be actively maintained for the foreseeable future.