- Do we need an attorney?
No, follow the VJ guide already linked in this thread. This is assuming that she has no legal and criminal issues, and you don't have serious convictions either.
- Is it advisable to start the process now or when her OPT expires?
Right now. Waiting until her OPT expires makes no sense at all.
- Should we worry about the ceremony and photographs given our time and travel together?
I wouldn't. We had a courthouse wedding, no pictures, no witnesses. We generally don't take pictures.
However, you do need to show proof of commingling of finances and a joint life together.
If your landlord won't add her to the lease, which does happen, have him write a letter that he knows you're living together.
A joint bank account should have money coming in and out from both of you. Having a joint bank account that only one person is obviously using could be worse than not having one.
Do you have renters and auto insurance? Add both of you on it. Cell phone? Get a joint plan. Other bills? Add both people. Health and dental? Add both if you can. Pet insurance? Add both as owners. This is much better evidence than pictures.
Trips together are great, too. Domestic trips are good too, if you book flights/hotels/AirBnbs together.
- How long should she expect to not be able to earn an income while change of status is processed?
That's why you should do this now. Do you, yourself, make 125% of the poverty line or more? Otherwise, EAD is currently taking longer and longer, 5-7 months is now the average. It will only become higher.