Questions about safety and reversibility of SD card partitioning. In connection with my previous problem, I want to dedicate part of my memory card to the condition of the internal memory using the application Link2SD. I know that I should create a second partition "for the apps". So I have questions about the process of partitioning (to be sure that I won't break something, or I won't do something that I won't be able to reverse):

1. To make the partitioning should I deallocate (remove) the main partition (G or another letter, NTFS logical), then create the first partition (G, Primary, FAT32), then create a second partition (Primary, ext2)?

2. Can I reverse the above process? By simply remove the two partitions and return to one big partition (G, NTFS logical)?

3. In the Android's filesystem, files from memory cards are available at the path /storage/extSdcard/. Will after partitioning the path will be still available or changed?

4. I have a strange path /storage/sdcard0/. For what it is responsible? Will the partitioning can change this folder?
Basically your approach is sound, with some minor adjustments I'd suggest:


You could do that. But it would be easier to simply shrink the existing partition. Using the right tools, that would even keep the data.
Of course you can, but you'd lose the data from one of the partitions: Simply remove one partition, and resize the remaining one to fill the entire card. But do NOT use NTFS :) It must be FAT then again, as it was before partitioning.
Depends on your device/ROM. If /extSdcard was, before repartitioning, the place you found the external card, after repartitioning you should find the first partition there. If not, simply use a terminal app (or adb shell) and issue the command mount (or, possibly easier, df) to list all mounted partitions and find where it went to. Should be the only one using FAT, so easy to tell ;)
That "strange path" points to your internal SD card. In case you wonder what then /sdcard is pointing to: to /storage/sdcard0/ (it's a so-called symlink).