Lens advice please for new convert coming from DSLR

There are a lot of questions here.

Let's start with the 18-135. Great lens. It is the best super-zoom ever made, by anybody. All-metal, professionally sharp, close-focusing, weather-sealed - what's not to like? It's on par with the 18-55 as far as IQ and focus speed. The IS is at least one stop better. The IS on that lens is amazing. It is far better than any IBIS you've experienced. Downside: It's slower, but only about 1/2 a stop compared to the 18-55 and 55-200. It's big and heavy. That's why I ended up selling mine. I just didn't like the way it felt and balanced on the camera. I personally prefer the 18-55, 55-200 pair.

55-230. At full retail maybe it's only $100 cheaper than the 55-200 but I bought a brand new one on eBay for $150! That is a lot cheaper than the 55-200. It's about 1/2 a stop slower than the 55-200, but it's got better reach, and is on par as far as IQ, AF and IS is concerned. It is a whole lot lighter, but the build-quality is not in the same league. It is definitely worth considering if you only reach for a tele-zoom occasionally or weight is a critical factor.

You mentioned you enjoy fast primes. I would not have a system that didn't include at least one fast prime. For me, it is a necessity. Which one? It depends on which focal length you shoot the most and/or what other lenses you have.

If you go with a two zoom kit or the 18-135, I would probably go with the 35 - either version. The 1.4 is faster and maybe a little better optically (although some reviewers hold the opposite view). The f/2 is smaller, focusses faster and is WR. If WR is important to you, the 18-135 and the 35 F/2 make for a very small, versatile and weather-sealed kit.

If you decide on the 18-55 and only want to carry two lenses I would recommend the 90 f/2. That lens is absolutely kick-ass. It's not IS but is veryfast. It is superb for portraits, kids, pets, landscapes, semi-macro shots, sports and birds (if you can sneak up on them ) The 18-55 and 90 make a sensational two lens kit.

If I were faced with a 'desert island' scenario, I would forgo the zooms altogether and take the 16, 23 and 90. But that's just me.

P.S. I have not tried the Samyang 300, but I have owned a few other reflex lenses over the years (good ones - Nikon, Vivitar series 1, Minolta) and have found them to be mostly useless. Toys more than tools. I learned a long time ago that buying cheap alternatives to good glass is never money well spent.