gar usually dont do too well with cichlids. try tankmates that are more passive...gar tend to get bullied fairly easily...unless the tankmate is small enough to be a meal. and yeas florida/spotted gar typically max out at 18-20 inches in captivity...with the rare 2'+ fish (which i have never seen with my own eyes).
yes...but they still reach sizes that most people cannot house...it would be best not to derail someone elses thread and just go ahead and read some of the stickies and search some past threads...you will likely find the info you are looking for.