Is this a 100 Ah battery or a 106 Ah battery?

Both numbers are on the datasheet and they describe different discharge rates. The nameplate is 100.0 Ah at the 10-hour rate to 1.80 volts per cell. Drain it more slowly, over 20 hours, and the same battery delivers 106.0 Ah. Size your reserve calculation against the rate your load draws, which for most telecom strings is the 10-hour figure or faster.

Will four of these fit a 23-inch rack shelf?

That is the geometry the case was drawn for. At 4.33 inches wide each, four units sit across a 23-inch shelf at 17.3 inches of battery, leaving room for intercell cabling and air. Confirm your shelf depth against the 20-inch case before ordering, and send a photo of the tray if you are unsure. We would rather check a dimension twice than process a freight return.

Can I add these to a string of older LPF units?

Match the whole battery, model line included: same model, same age, same lot where possible. A new cell dropped into an aged string gets pulled down to the weakest unit's capacity, so you pay for 100 Ah and get whatever the tired cells allow. Replace the set if the string is more than about two years into service, or match units only on a young string with a documented single-unit failure.

Can this ship by air to a remote site?

Yes. The LPF12-100A is a sealed non-spillable battery, IATA approved for air freight, so a failed unit at a fly-in site can be replaced without waiting on a barge or a seasonal road. Tell us the destination when you ask for the quote and we will price the lane both ways.