A lot of folks have given you great advice, I will just add my thoughts.
K1 and CR1 timelines vary. To give you an idea and help you make a more informed decision, look at the different processing times for I-129F and I-130. Also check timelines from people here that have filed.
USCIS processes both I-129F and I-130 equally, maybe different processing times though. One reason they would reject your petition is if they believe you are already married.
This is subjective as each has their own situation. We went the K-1 route because it was the fastest at the time and we wanted to start our life together quicker.
If the USCIS officer believes you are married—even if you are not—your petition will be denied. From your later post it sounds like you had an engagement ceremony. I wouldn’t include any photos of this as part of your proof of relationship. We did not include any pictures of our engagement, but just had a lot of other evidences instead.
As I said in my response to #3, everyone’s situation is different. In my situation, if I was filing today for my wife, I would have a nice wedding ceremony in the Philippines with all her family present and then file CR-1.
Hope this helps you in your visa journey. Please use the resources here on VJ to help you.