Self Sponsord visa for Parents/In laws: Questions

[SWAPNASRI]

Hi,

My husband and I are working in the US for some years now and we are planning to get visas done for both our parents so that they can come and visit us before we go back to India for good.
I had some questions regarding this.

1) My parents and my in laws have filled in separate DS160. My parents have mentioned me as the close relative and my in laws have mentioned my husband in their respective applications. They are however going for interview on the same day and time. Will there be any issues? They will not be travelling to US together however we thought of booking their interviews together on the same day so that they will have company.
2) They will be self sponsoring for the visa. Both are retired and have around 20-25 lakhs that they can show. Is that sufficient for a visit of 3 months?
3) We are planning to send an personal invitation letter too just case. Would it be sufficient to e-mail it across or should we be physically mailing a signed letter?

Any help or inputs would be welcome.

[peace999]

yes, they can appear together. No issues there.
20-25 lacs is good enough savings.
you should send an original invite with copies of your visas ( also copies of H-1/L-1 petitions if any).
These days they hardly look at any documents but it is safer to carry the important ones, just in case.