Yes usually the last 10-5% charges slower. No issues though if you pull off the charger at 90%....wont hurt memory...basically charging from say 40-90% is good for a cells life span.
Few tips....load only about 70-80% full stems...and do not at all pack down..just level the top off so it does not stick above the end of the stem where it can touch the oven bottom.
Yes it will get warm at the higher temps....and pending on how long you set the on time to be. I normally use at 376F (191C) for the entire load and can normally finish before the 10 min auto off setting kicks in.
When you have the stem inserted into the vape..and the glass sticks up a bit with the lid down ( i never put it up for any reason), then you can use one of the rubber caps to put on the exposed stem top.. it will fit.
You should not have much burn off smell....as with all the arizers I have had. But I normally use a longer qtip and dampen it with ISO....then rub it around the oven bottom and side walls inside the air/stem path. Then go over with a dampened qtip with water and swab out again....let site for 5 mins and do 3 burn offs (just like you did)...then repeat the qtip cleaning....and your ready to roll. I do this will all my electric vapes for sure. Arizers seem to be the cleanest out of the box.
If you use water...or have a rig...get a WPA and you will be happy. I also highly suggest trying one of the bubble stems as they offer better tasting vapor and smoother. I get mine from 420EDC....check back a page or so and see the pics.
One last thing......having an extra battery or two is nice...you never want to have to wait for a battery to get charged. Sometimes that happens at the worst time when you really need to use.
Enjoy and welcome to the club!