I’ve posted about most of these SOO many times here, and have had support on these things, but the developers have never found any of them to be important.
Now, if someone from the Renoise team was to say “this is not important to us”, wouldn’t that be exactly what you are looking for - a clear statement that something will not make into the software? I mean, instead of teasing with “hey, yeah, that’s a really good idea. Let’s see what we can do about it” ?
Right now, I would probably do as people here suggest, take a break from a software that is obviously frustrating you. I know you have produced amazing music on Renoise in the past, so it’s a bit funny that things can go this way…
However, if you are willing to at least read and discuss the available options, let’s look at what you brought up
One: The ability to turn on an option that makes it so when you scroll through with the arrow/cursor keys through the song, it always plays what’s on the current line.
If I’m not mistaken, that sounds exactly like pattern follow (Scroll Lock, or the little icon in the transport).
(Btw: among the first things I suggest people should learn in my proposal for arevised quickstart guide).
Two: The ability to make it when you set the amount of lines to skip when you enter a note or hit the delete key, that it can also affect just hitting the arrow keys, so you can enter notes quickly with lots of lines skipped and still correct errors easily when in a song that the pattern has been expanded.
In preferences > Keys you have the alternative shortcuts “Move to Next/Previous Row with Editstep”.
By default, this is assigned to CMD/CTRL + SHIFT + Up/Down, but you can change that yourself.
Three: Some sort of method of smoothing or doing a pornamento when a pitch is cut to a certain value via the pitch bend wheel via midi.
You mean, when controlling a plugin? Because for sample-based instruments, some workarounds exist (check this link).
For plugins, I’m thinking that smoothing is something the plugin should handle itself.
Four: The ability to do slides on samples via the pitch bend on the keyboard and be able to use the sustain pedal to do note-off commands on samples.
My full answer to that is located in this topic
https://forum.renoise.com/t/how-do-i-make-the-sustain-pedal-affect-samples/42099
Five: When recording a live audio track, the ability to make it insert the appropriate C note in the exact spot one starts recording.
It’s a bit specialized I think, but I have made something called the Recorder, which will automatically insert recently recorded notes. Mostly an experimental thing I made for improvising with a friend of mine. You probably don’t want to waste time on this tool, but what you suggest is entirely possible to script.
Six: Have the option to switch back to the old way of handling live input. Have the option to turn on and off the old chord mode. Have quantize options for after notes have been entered.
Hey, I count three suggestions in one line 
Yes, the “chord” mode is now specified per instrument, which is far better IMHO - but it would seem that we forgot to add a keyboard shortcut.
Regarding note-quantize, it’s tricky stuff. I definitely agree that realtime recording of e.g. piano could use some refinement. But if we are talking about “quantize that change notes to snap to nearest line in both directions”, then this is a bit tricky. Right now, if you want a 1:1 relationship between what you hear and what gets recorded, try setting input quantize in the instrument as well?
Seven: 1024 line limit instead of 512.
Ah yeah, good one. Instrument phrases could use this too (hell, why not even more lines?).