Mazda Forum - Mazda Enthusiast Forums - RPM and Shifting questions

Hello! I recently purchased a used 2015 Mazda 3 Sport, with manual transmission. Although I have driven other manual transmission cars before, this is the first one that I have owned. All of the vehicles I learned to drive in were 5 speeds, with V6 engines. Obviously this car is a 6 speed with a 4 Cylinder engine. So, please forgive me if any of the following questions seem obvious to others, as they are new to me.

My first question is about my rpm's. Generally speaking (correct me if I'm wrong), it's ideal to cruise at around 1,300 to 1,500 rpm for maximum fuel economy and reduced engine strain, as long as you're not lugging the engine. I will usually shift up around 2,000-2,500rpm. When I am in going about 40-45mph, I will be in the 1,500 rpm range in 6th gear. When I'm on the highway at 60mph and up, I will be at a sustained 2,000-2,500 rpm. Is this high? I realize there is a lot of room left in the power band for acceleration, but I wasn't sure if my rpm's should be lower at cruising speeds in 6th gear? My fiance drives an automatic with a V6, and her car seems to stay around 1,500rpm at 65.

My second question is regarding some shifting concerns. In the past few weeks, I have noticed some resistance in the shift lever while changing gears. Correct me if I'm wrong, but I was under the impression that as long as my foot is fully on the clutch pedal, I should be able to move freely within the gear box. Yes? I have never had to jam the lever into gear, but I can feel in my right hand that some times it takes a second to "click" in, before I even take my foot of the clutch. Sometimes it takes longer than others, but it usually goes in. There have been a few occasions where I haven't been able to get in gear. I was at a red light in neutral, and when I tried to shift into first, it wouldn't go. Only thing I could do was turn the car off, and on again, and then take off in first. Other time was trying to shift into 5th, and again, couldn't quite get it into gear. No grinding sounds were happening, so I just kicked it back into 4th.

I have noticed that the resistance seems to happen at different rpm speeds. Usually if I shift at a lower rpm (1,800-2,000) I will have little to no resistance. But when I need to utilize a little more power at higher rpm's, I can feel more play in my right hand. This isn't always the case, but seems to be more frequently. Frankly it makes me a bit nervous. Could the pressure plate be going? Maybe the clutch isn't fully disengaging?

I am under the impression that the engine and transmission are still under warranty until 60,000 miles, and I am wondering if these are issues I should have my local dealership look into. The car was bought at about 40,000 miles, and I can't speak to how the previous owner has driven it in the first parts of its life as it was bought at a dealership. It has never been in an accident, and seems to have been well maintained other wise. Has anyone had similar issues, or taken advantage of the warranty for similar repairs? Or.... are these things normal and I'm crazy? All open recalls have been updated as well, and there are no check engine lights on. Thank you! Sorry this was such a lengthy post.