You can purchase a replacement LCD Screen and Digitizer for your Samsung Galaxy S7 Edge right here. Unfortunately they do not offer the Samsung Galaxy S7 Edge in a rose gold color, so they do not offer a replacement screen in that color either. I have, however, linked the gold version, which is the closest to rose gold.
Your laptop's internal storage can not be upgrade because eMMC storage is soldered to the motherboard. There are 2 alternatives however. You could either buy an external HDD or SSD that plugs in to your laptop via. USB (you can get a 1TB HDD for just over $50). You could also purchase a Micro-SD card to expand your storage as a Micro-SD card reader is already built in to your laptop. I have the same laptop as you and I faced the same problem. I chose to buy an external 1TB HDD off of Amazon. So far it has worked very well. Here is a link to the HDD, right now it is on sale for $45.
This could possibly be a battery issue. I, however, would do a factory reset by following the steps below. Keep in mind, doing a factory reset will erase ALL of the data on your device. 1. Turn off the phone completely. 2. Press and hold both volume up + power buttons on the phone. 3. When the Android Recovery menu screen shows up, release all keys. 4. Navigate to and highlight "Wipe Data / Factory Reset" using the volume down key and press power to confirm. 5. Navigate to and highlight to "yes -- delete all data" and press power. 6. Remember, all data will be lost! Before doing a hard reset backup all important data. After hard reset is done select "reboot system now". Press power to reboot the phone.
First, you should do the obvious; if you haven't already you should wiggle the button around in order to get it loose. I'd also blow it out with canned air, you should be doing this on a regular basis anyway. If all else fails, you may have to disassemble the controller and clean it from the inside.
First I would try the obvious. Blow out the audio input with canned air, check your settings, restart the computer, reinstall/update drivers, factory reset the computer. If all else fails, you may have to replace the audio jack. I haven't been able to locate any guides or replacement parts for this on iFixit so I would try to google it. If for whatever reason you aren't able to fix it yourself, then take it to a professional.
Yes, it is possible to replace wireless card in this laptop. You can purchase a new one here. As for a replacement guide, there is not yet one available for this laptop and I am not able to create one as I don't own this laptop. I recommend searching Google if you haven't already.
Although not a requirement, I definitely recommend conditioning your battery right after you install it. After that you should charge and fully drain your battery on a regular basis in order to get top performance.