Firstly Bella is absolutely adorable - that face
Sedation is like a milder form of GA. Usually with GA people/animals get breathing tubes because you're totally knocked out, whereas with sedation you're asleep so you can typically breathe on your own and you're not totally knocked out, you're just asleep. People/animals come around a lot quicker when they have been sedated vs under GA.
Whether sedation is a good idea for a lump removal - I wouldn't have a clue, so I would definitely be guided by your vet on that one.
If it makes you feel any better I have a piggie who turned 6 last month who has had a fatty lump for 3 years, it hasn't grown (touch wood) and it doesn't bother her at all. We didn't have surgery because she suffers with IC and the smallest of inconveniences upset her and stress her out, she gets upset if she accompanies her sister to her sisters appointments, so the thought of her going through that to us just didn't seem worth it.
Should you remove it? That's only a decision you can make. I guess you need to take into consideration, (1) where it is (2) is it going to annoy/effect her (3) depending on where it is, if it grows could it push on any important areas (4) are you going to be an anxious mess if you don't do it
Try not to worry (hypocrit of the year award goes to me) I know it's hard but if it is just a small fatty lump, and it's not currently bothering her, then it's not an emergency, so you have time to think over the pros and cons. If you do decided to have it removed hopefully you'll be in a better head space as you will have had time to process rather than rushing in to it.
Good luck x
