invite address question

ok...so i think i'm finally ordering my invites this week as soon as phyllis gets back to me with prices...

i'm trying to finalize my guest list. here are my questions:

1) on the outer envelope is it
Mr. and Mrs. Robert Smith??

OR

Mr. & Mrs. Robert Smith??

2) is it okay to word the inner envelopes like this:

Eileen and Robert??

OR

does it have to be Mr. and Mrs. Smith??

OR

Mr. & Mrs. Smith??

Thanks!!!

Outer envelope:
Mr. and Mrs. Robert Smith

Inner envelope:
In the Martha Stewart etiquette article she wrote that it would depend on how personal you are trying to be and how formal your wedding is...
any are fine...IMO, I would write whatever it is you call them by...I addressed the inners with the 'loving' names I called family and friends (for example my friend's name is Israel and I wrote Isy and Guest...