Does diagonal or vertical position affect the lifespan of a SSD drive

It shouldn't matter which way you do it these days. But there's one possible caveat of making it vertical:

Under situations where cooling is at premium and you don't have the means to increase cooling of your system, mounting the disk horizontally with the label facing upwards could be seen as an advantage, since heat rises away from the disk surface more efficiently than if the disk was mounted vertically. But even so, any impact on performance or disk lifetime would only be noticeable in years to come. Just thought nevertheless to make this note.

The short answer is no, you don't have to do anything special.

When you delete a file, you're basically telling the filesystem that the storage area reserved for the file on disk is now free for reuse. This is true for both an SSD, and a regular disk. The file data isn't really completely gone until something else uses some of that freed up space and overwrites it.

On a regular drive, there is essentially no limit to the number of times you can reuse a block of storage. Storage blocks on current SSDs will physically fail after a number of writes that is small enough to matter. SSDs avoid failing by doing something called wear leveling. This means the drive will try to actively distribute use over all blocks as evenly as possible.

So, while a file isn't really gone until the storage blocks get rewritten, the blocks tend to get reused/rewritten more rapidly on a regular disk than on an SSD. If you're concerned about data security, writing over a file then deleting it gives you some assurance on a regular drive (although there are more complications than you might imagine). This is much less the case with an SSD. Writing over the file will most likely mark the old blocks as free and write to new ones.