Trapeze All-in-one Stand Alone Pull up Bar

Can the top bar be adjusted to do chinups with a low ceiling?

how tall is the unit can I put it in a basement with a low ceiling ?

if you buy the stabilizer bar, will this reduce most of the 'wobbly' sensation? Maybe buy 2 stabilizer bars (one for each end)? How about sandbags?

Can I use this bar for gravity exercises with the proper boots?