Anton says:

1: I need more specific regarding tolerances, what do you mean: length, width?
2: This one depends on length of equipment you prefer to run. In general these are the NMRA standards for HO scale, but I am not sure of N scale since I model HO and On30 hybrid railroad:
less than 40′ cars http://mrr.trains.com/-/media/Images/News%20and%20Reviews/Reader%20Reviews/2011/09/Model%20Power%20HO%20scale%2040-foot%20boxcar.jpg (5.5″ in HO scale) would run as sharp as on 15″ radius curves. Radius is measured from the center of the track. European equipment with lots of compromise in underbody detail can even allow full length 90′ passenger cars run on 14″ curve but those look ridiculous and prone to derail when pushed backwards. Then 50′-60′ cars http://thumbs4.picclick.com/d/l400/pict/191983996243_/HO-Scale-Canadian-National-CN-209871-60-Foot.jpg (6.9″-8.3″ in HO scale) need at least 18″ radius to operate. Anything above that, 22″ radius should do like these http://www.enginehouseservices.com/product_images/j/137/74994353677979__87122_zoom.gif except for Walthers Proto passenger cars with close coupling and touching diaphragms and full underbody detail http://www.ovrtrains.com/images/P/920-9341-2.jpg.

Now, prototypical minimum radii vary too, but in HO scale to have trouble-free operation in all prototypical configurations, like push-pull I would advice 48″ radius for US equipment which is ~350′ radius in real life, and 72″ for European equipment (160m or ~500ft radius is minimum prototypical standard to run full length 90′ passenger cars without problems) due to buffers that overlap and lock when slide too far apart on S curves. http://i172.photobucket.com/albums/w17/waynec_kits/0-2015%20RR%20GONDOLA/buffer%20and%20chain%20coupler03_zpsgbaavj8e.jpg as you see buffers are in contact, on
S-curves they slide sideways. On curves less than 160m derailment can occur. If you have no space for prototypical curves, like most people, and have not bought any trains yet, I would suggest to stay with North-American equipment, it is forgiving due to absense of buffers especially in HO scale unless you really like European trains and are eager to go long way to make them operate as I do since I grew up in Eastern Europe.

As for N scale I do not know those dimensions but I assume they are in ~1.8 times smaller (160/87 ratio)

3: Same as with curves, depends on locomotive length. The bigger the angle, the less distance it will take to get from one track to another one, hence the sharper the radius. I am 90’s post-soviet kid and used to Soviet turnout marking e.g. 8 degrees, 400m diverging curvature so I do not understand anything in turnout numbers and still trying to make sense of European turnout # system which is again different from American. I noticed #6 turnout by EU designation is about twice as long (broad, I refer to length of straight piece of track before diverging track leaves the straight part). My observations in local model railroad club show that #6 is minimum for trouble-free operations with passenger and autorack equipment and #8 is the minimum where passenger equipment looks prototypical with close coupling. I assume that curvature on #6 corresponds to around 30″ radius and 40-45″ radius on #8.

4: Distance between parallel tracks: 2 inches between track centers in HO scale, I assume 1.125″ in N scale (160/87, rounded to the closest 0.125 of an inch) but as I do not model N scale I could be wrong.

5: tricky question again. Do you run double-stack containers, bi-level passenger cars like superliner? I suppose 3 inches makes it for most equipment, but I am not sure of prototypical reference clearance of height. I used 3.5″ height for EU overhead wire locomotives and with addition of On30 trains – 3.5″ barely makes it (taller than imaginary wire of HO scale at ~3.25″).

6: Since ~50mm is between track centers, leaving about 10mm between adjacent trains, I would assume 20mm from track center should be the edge of platform for most trains. However if you plan to run anything oversized which could be wider http://model-railroad-hobbyist.com/sites/model-railroad-hobbyist.com/files/users/JeffShultz/img_1027_800x600_bmann_schnabel.jpg http://www.chasingheavymetal.com/blog/wp-content/uploads/2010/09/6G2_0034-Version-2.jpg I have no idea, I would advise at least 25mm on straight sections of track and a big NO to platforms on curves like these http://img-fotki.yandex.ru/get/9510/19099752.3e/0_9f40e_b76d4f2c_XL.jpg especially when platform is on the inner side of the curve.

7: For tables and charts I cannot think of any links but above indications should give you an idea of what to expect.

Since I model only HO-gauge (HO scale track rideable trains which includes HO scale, On30 1:48 30in gauge and Sn64 (Japanese 1067mm gauge in 1:64 scale)) refer to someone else for N scale advise.