This will be a briefer reply because I'm on my phone, but I hope to succinctly answer your question/concern.
From my understanding of the Texas Method, your approach for Monday is correct; Wednesday is a "lighter" day (90% of what you did on Monday for doubles or triples), and Saturday is a day to push for a new 5RM. I'd say to follow your protocol: see how you feel. If you're feeling strong enough, make the judgement call to push for either a 5RM or a new single. Sometimes, you can do both in one day if you're really feeling good. Your "feel" will dictate how you approach Saturdays, to include the weight you put on the bar for Mondays.
As for your experience with the type of squat to your classic lifts, I would say that's normal. Each lift relies on the build up of your front squat; the back squat is to develop raw power and strength, whereas I feel the front squat builds applicable power and strength, if that makes sense. The nature of the bar being slightly forward of your center of gravity to begin the front squat already puts a strain on your lower back, so it's ok if you felt like poop while doing your snatches after heavy front squats. Just make sure you're not losing posture and fatiguing yourself faster with poor form on each movement. Remember ... Efficiency!
Javier A. Sanjuan
Olympus Barbell Club
Dear God, please help me lift heavy and be awesome. Thanks. Amen.