Re: new guy and never really fished before
Look into "steeple cast" if you are really concerned about keeping the line off teh water behind you. Never fished out of a kayak, so I have no ides if it is needed.
Tippet breaking. Nylon is fairly unstable as we use it. It has a short shelf life, is UV sensitive and doesn't like repeated exposure to hot days. If you are breaking your tippet that easily, the spool is probably dead nylon, so long as you are lubricating the knots before you pull them tight.
As for drag, I have mine set to minimum almost all of the time and only turn it up when I need it. I don't like having the springs tensioned all the time, and I use reels with spring tension click-pawl drags because I rare need the drag as it is.
As far as leaders and tippets for a 5 weight and a 7 weight can be very similar. Both could easily take a 7.5' or 9' 4x leader with no problem. Generally speaking, you will be running slightly heavier leaders and tippets on the 7.
I use a 3-weight, a 5-weight, & 7-weight.
A 4x tippet rarely sees a the 3-weight and when I have used it I have considered it "heavy".
A 4x tippet is common on my 5-weight and is the top of what the rod sees generally.
A 4x tippet is uncommon on 7-weight, and when I do use it I consider it "light".
For a little perspective on that: Am kind of a small-niche guy. I like small rivers and soft hackle looking for trout, hence the 7'6" 3-weight. I use a 9' 5-weight on larger water again targeting trout. The 7-weight is for targeting large nocturnal browns, and that turned into river run smallies and now I am using it to figure out the warm, still water stuff for large mouth.
Hopefully that sheds some light on the leader thing. So, the leader on your 7-weight will work fine on your 5-weight.
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