1) Yes, you can. The 250 GB Samsung 850 EVO SATA version is a 2.5" drive that fits perfectly into laptop HDD caddies.
2) The restore disk is for recovering your Windows installation in case it gets damaged by a virus or adverse changes to the system.
3) You don't need many of them. Those apps are often pejoratively called "bloatware," which is software created by the manufacturer of a computer to distinguish their products from competitors. Some of the software is very helpful though. Up to you to decide which ones you need. They don't really take up a lot of space.
1. Yes, You can change your HDD with a regular SATA drive.
2. You can probably repair/restore your OS if something gets messed up. This would most likely bring the OS to its stock state along with the apps and everything, but I'm not 100% sure if it restores the additional software as well.
3. If you don't need some of the apps you should be able to uninstall those which you don't really want.
edit: Sorry, it seems like you've been given an answer while I was typing.
I dont know if I can place a question here .
But about the problem I have with the SSD.
I heard that its a problem with the latitude E4750.
Can I the a picture after open up the laptop and let you see the parts ?
What exactly is the issue with the SSD? I didn't understand if there was a problem you were trying to describe. As for the picture - sure thing, you can post it. Just make sure that no serial numbers are visible, just to be on the safe side. I'd also suggest that you don't open your laptop yourself, before you make sure what voids your warranty and what doesn't.
I don't see a regular HDD in addition to the msata SSD. I could be wrong, but I think you only have the option of one HDD/SSD at a time. It looks like the msata drive has an adapter on the end, and that plugs into the connector where a 2.5" HDD/SSD would take the place of the msata drive if it wasn't there. In a chart of specs for the various E7450 configurations, it shows a choice of either a regular 500GB HDD, OR an SSD, but not both. None of the reviews I read mentioned the ability to add a second HDD/SSD.
Unless I'm misinterpreting the question. If you are just looking to swap the msata drive for a full size EVO 850, it appears it can be done. Your statement, "install additional 256 samsung evo ssd" made it sound like you wanted 2 drives.