Re: Ouestion on Jobseekers Allowance for two adults.
If both of you are seeking work, then you can both sign on.
If one or both of you qualify for Jobseeker's Allowance (which as you rightly said is means-tested), and if you both sign on, the total amount of money paid can't exceed what would be paid for a family with 2 children - so there is no financial gain in both of you signing on.
If both of you sign, both of you may get PRSI credits, which may count later in life for pensions, etc. If you claim for your wife as a qualified adult (or vice versa), only the person signing may get credits.