You don't need to add more RAM, that won't speed up your compúter. Buying a faster drive will, such as a Solid State Drive instead of a Hard Drive which you currently use. I won't be able to help guide you through changing drives, sorry.
You can't remove critical things from the startup tab. Yes, anti malware/anti virus programs usually are back in the startup list once you started them again.
An I7 will speed up your computer, but not launch applications, or anything like that quicker, just heavy use such as rendering, that's when you'll notice the difference. Also, depending on laptop, it may have a soldered CPU to the motherboard, or the power requirements are too high, or the manufacturer don't want people to upgrade, so even if it's the right socket, it may still not work.