Your banjo is comfortable when you are. Freezing temperatures should be avoided. If the banjo is left in the cold during shipping or transportation, let it warm up for eight hours indoors before opening the case. If the banjo warms up too fast, the finish will crack. Never expose the banjo to direct sunlight or leave it in a car that is parked in the sun. Excessive heat will break down the glue joints. High or low humidity have less effect on a banjo than other fretted instruments.
The most common adjustment to make on a banjo is head tension. A new head continues to stretch a little for a month after installation. A head that is too loose will allow the bridge to sink and the strings will lower and cause buzzing. The sound may also suffer. Using a 5/16 inch bracket wrench, go around the rim and give each nut a quarter turn. If the nuts seem to turn easily and the strings are still too low or the sound is still poor, give each nut an additional quarter turn or two. Heads can last many years, but if they are tightened too tight, breakage will occur.
The string height is also affected by the angle of the tailpiece. A high tailpiece angle will let the strings rise up a bit. A tailpiece that is angled down close to the head will push the bridge and strings down enough to lower the string height. The tailpiece angle can also affect the sound of the banjo.
The easiest way to change the string height is to change the bridge height. Within a dozen 5/8 inch bridges some will be accurate, some will be a little higher and some a little lower. The overall variation can be as much as 1/16 inch. This is enough to make a big difference in the way a banjo plays. Buy or try several bridges when replacing your original bridge, which should last several years.
Banjos traditionally have nickel plating on the metal parts. This nickel tarnishes as soon as it is touched. To minimize tarnish, wipe off the banjo with a high quality paper towel after each use. If tarnish is allowed to accumulate, Simichrome polish will remove it.
Your banjo is finished with nitrocellulose lacquer, the traditional choice. It is expected and normal for it to check and crack with the passage of time. Keeping it out of the light and in the case when not in use will delay the inevitable aging process.
Eventually the strings will wear grooves in the frets and cause buzzing. This usually takes several years to occur. The frets on a new banjo can be leveled or filed several times to remove wear before replacement is necessary. Fret leveling can be done at the factory or by an experienced banjo repairperson.
Your banjo has an adjustable truss rod. To access the adjustment nut remove the strings, neck brace and endbolt. Slide the neck out of the rim. The nut receives a 1/4 inch nut driver or head tightening wrench. Turning may be stiff and the nut can be broken by an inexperienced person. This adjustment is rarely necessary and only used to straighten a bowed neck and does not change the action or string height.