Will this jack work on my vehicle, or do I need a different capacity?

30-ton capacity covers nearly all street cars and full-size trucks. Check your vehicle's curb weight in the owner's manual and divide by four (one jack per corner); if that number is under 7.5 tons, this jack has plenty of headroom.

Do I need to pump this jack up before storing it, or can I leave it flat?

Store it in the retracted (lowered) position. Leaving it fully pressurized for extended periods can stress the seal; the welded design means you won't have slow leaks, but resting it flat is still the standard practice.

What's the deal with welded versus non-welded bottle jacks?

Welded bottles have no threaded seals to degrade over time—they hold pressure indefinitely and handle rough shop use. Non-welded designs can develop slow leaks after years of temperature swings. Welded is the pick if you want durability.