A power supply that can supply 12V 5A (that is 60 W) should be good enough to use.

When charging lipos The charger detects how much MA to put in so you don't have to set that on the charger.

In your first post you mentioned the battery says to not charge more than 1 A. I think you misread and it said 1C.
Which means that you can safely charge that lipo at 3A which will give you a charge time of about 1 Hour.

Also, that charger is rated for a maximum charge current of 5A.