Water: Water level s/b 1/4" to 1/8" below the split ring that extends down into the cell. Just touching is absolute max and even then may cause some electrolyte to be pushed out of the cell causing corrosion. Check levels every 4 months. More in high use or high temperature conditions.
Charging: Getting the battery to 100% tip top charged before storage is very important. Voltage needs to be 14.4 to 14.8 volts on the battery terminals 2 to 4+ hours to get a full charge. What are your charging voltages?
Float charge in the 13.2 to 13.4 range. Temperature compensated is best in climate extremes. If you cannot float charge... give them a good charging 24 hrs and then disconnect a cable. Clean the battery tops as dirt/crud will conduct and discharge the battery.
Careful how you handle the terminals during installation. Too much twisting or banging can cause the seal around the terminal to break and contribute to corrosion of the terminals.
Don't overly discharge the battery. Down to 12.2 volts or about 50% is time for a heavy recharge with 14.4 volts for at least 3 to 4 hours. OK to charge more often when in use.