Hey mate, good & valid points 
One. Yep, a defo possibility & something serious to take into consideration for anyone who's past the point of simply losing weight & now taking it to a different level of body composition goals etc
100% something to keep tabs on
Myself, I'm far past the point of being concerned about it & I can completely remove myself from it emotionally & look at things objectively
I don't even track my food hardly ever anymore & I haven't stepped on a scale in months
Here's my fitness/nutrition lifestyle atm
mon-fri, I go for a power walk every morning for 45/60 mins while listening to an audiobook, loosely track protein and try to get about 100g every day, but don't always & don't stress over it at all, pretty much eat the same thing most days out of convenience & time/work etc & just eat intuitively never going past the point of feeling full
I also try to lift weights 3/4 times per week, usually every other day, sometimes less often & miss a few days if my body feels like it needs a rest
weekends - anything goes lol
for example, was at the mother in laws for Sunday dinner yesterday & to celebrate my sister in laws bday... ate a sh!t load of rocky road cheesecake after dinner, then had more.... then had carrot cake, then after eights, then more cheesecake lol
I don't feel guilty about it & I won't try to balance it out by exercising more or eating less... I enjoyed it, I'm already in decent shape, so I'll just move on
In fact we usually go out or meet up with friends most weekends & indulge a bit. We're hosting a party this weekend, already stocked up the treats & booze
Basically, I've been at this for so long that I can use my intuition in place of tracking now (although I don't advise people to do this until they become much more experienced, as their guesstimating will usually be WAY off)
I figure I'll be fine if I'm exercising a good bit (5 days power walking, 3/4 days strength training) eat mostly good food & never go past feeling full.. all that for 5 days, then not worrying about it at all for the other 2 days.
As far as the self observation thing, here's an AMAZING book I think everyone should read
It's about a psychiatrist, Viktor Frankl, who became a nazi prisoner of war, who while himself imprisoned & pushed to the brink decided to make a purposeful effort to observe both himself & his fellow prisoners & document the whole thing
Myself, someone who coaches other people into getting into lean condition, I need to also be fully aware of how every aspect of the journey feels, physically, mentally & emotionally.. so I constantly test everything on myself so I'm in a relatable position, rather than just a text book position.
Two. As far as lean bulking, basically putting on as much lean mass as possible, with minimal amount of fat gain
fat gain is inevitable when you're in a calorie surplus & if you do things right, a 50/50 split is typically a good result,
at my stage, I can gain approx 1lb of new muslce per month, taking into account the inevitable fat that will come with it, that puts me at 2lb per month... if I go past that, I'll won't be gaining extra muscle, it will just be extra fat
As far as getting lean in order to bulk, this comes down to nutrient partitioning.... if you're over about 15%, you'll gain more fat than muscle, if you're under or closer to the 10% range, you'll gain more muscle than fat
So nope, when gaining muscle I won't be able to stay as lean, I'll also gain fat, which is why I'm letting myself get a bit leaner than most would like or allow themselves to...
I'm probably going to fluctuate between about 8-15% going forwards, which means if I'm at 8%, I'll be able to spend the best part of a full year in a calorie surplus & adding muscle whilst remaining relatively lean, which means I won't ever have to spend a prolonged period of time 'dieting' down ever again... maybe a few odd weeks here and there if I feel the need.
Hope this makes sense?
The very first thing I'd say is to get into a place where your comfortable with your body, then go from there
