I applied for citizenship by descent. Just follow the instructions, make sure you answer all of the questions, check every applicable box, and put N/A in any space not applicable to you. You can take copies of your documents to be certified to a Canadian consulate if you wish to; just be sure to make an appointment first as they do not allow walk-ins.
Not at all, the instructions are pretty straightforward.
The estimated timeframe on the IRCC website is 5 months; however, others on this forum who are also citizens by descent have said that their timeframe was just around 2 months. My application was sent to Program Support because it was considered non-routine, so I do not have a timeframe to give you.