I learnt a lot about Fridah Kahlo here - what a fascinating life story! Their audio guide is excellent ... the best I have ever seen at any museum or gallery.
There is always a line to get in but it’s usually the shortest on a week day morning. You can get tickets online in advance too but there is a separate line for people with tickets and it doesn’t move much faster (so I don’t understand the point of getting tickets online in advance). We went there on a Thursday and arrived before noon so the wait was relatively short (5-10 mins). When we walked out around 1pm, the line was a lot longer.