2.) What should I note if I want to change the hard disk partitioning!
For God's sake, always back up the data, because the trouble is great, if it happens, you mourn the data for years afterwards. And do not play around on disks where data is stored.
Even a very experienced user like me did it, I do not believe it myself after 20 years.
How can something happen to me? NA YES, I'll describe it here, even if it does not quite fit into the FAQ, but then it will make you understand that it can happen.
So 20-21 years ago, I had two 20 GB hard drives, then IDE, and I always had the complete data mirroring on the second, at that time with a DOS PARTITIONER (DOS4GW). When PC exchange both hard drives are gone and the second served only as a nostalgia backup. When I decided one day to format the hard drive only once, I put it on the IDE connector. The layout of the disks was still the same, unfortunately, the old backup disk has logged in as a master and I thought, so the original is the backup. And formatted the original, partitioning under DOS I could not recognize that.
The trouble was great, but I was still lucky, because the hard drive was still formatted FAT and with the old UNFORMAT command, who still knows him, I could win at least 85% of the data, but as I said the 15% I still grieve after.