Hey there! Moving up to mech mods will be a slippery slope! If you happen to like shiny things, you'll get one mech mod and the thing will multiply into many!
With that in mind, here's my personal experience with your questions.
- Since mechs use whatever voltage charge is left in the battery, as the battery drains, you'll definitely notice a diminishing quality in your vape. Whether you notice the flavor, vapor production, or throat hit drop, that will be the time to change your battery. When I first started using mech mods, I would notice the diminishing vape. I would throw the battery into my SVD and check the battery level. I notice consistently that I want to change batteries in my mech right around 3.5-3.6v.
- With maintenance, you'll need to wipe down your contacts on a regular basis. I usually take my mod apart and clean the pins during an atty change, when I rewick, or when I rebuild. I do one of those things often enough, that I usually keep my contacts in tip top shape. When I clean the contacts, I just use a cotton swab soaked in 91% isopropol alcohol.
- I find mech mods to perform best for me when sub-ohming. Usually I won't put something that is greater than a 1.0 ohm coil on a mech. I'd rather use my regulated mod, like a Provari, if I go 1.1 or greater. I have vaped my genny that was built to 1.5 ohms on my 4nine clone before. I did it as an experiment and was glad I had my Provari in my other pocket. Because the quality of the vape on the mech started out ok at full charge, but quickly diminished after the battery dropped below to 3.8 volts.
When I started
vaping mechs, I only used them part time. I felt more comfortable with my regulated mods. Nowadays, I'm much more comfortable with my mechs, but still only take them out on rare occasions, because they're usually topped with sub-ohm builds that produce a lot of vapor. Not my style to blow big clouds in public places.
Good luck to you! The learning curve is there, but it's not bad. And you may end up collecting a bunch of shiny stainless, brass, or copper tools that will give you a heck of a vaping experience.