I did an extended Water Fast and it was difficult but effective. I had many failed starts of a few days to a week before I was able to stick to it for an extended period.
1. I couldn't go to functions involving eating most days. I'm sure there are many people out there who can fast and hang out with people in an eating situation. I can't if I want to continue fasting.
2. After the first week it was easier, then much harder, then terrible, then I felt like I didn't even need food anymore. I have no real advice on this one.
3. I turned back to a vegan diet after I had fasted 92 days (starting slowly with juices). I gained 20 lb of 100ish lost back the first year, but my body composition was absolute crap. I have since switched to a plant heavy ancestral diet that includes meats and would never recommend a vegan diet after thorough research (please don't hurt me over the anti-veganism thing).
4. Definitely listen to your body. Fatigue and weakness are one thing, but weak muscles, especially if they start cramping or your heart is beating irregularly or racing, that can be dangerously low K levels. With a healthy pre-fast diet it is unlikely you'll have an issue unless you go on an extended water fast. I didn't feel the need to add electrolytes until about day 60 I think?, but people can have life-threatening issues after just a couple weeks. So if you go long, please be monitored by a healthcare professional.