Atlas map nodes completing

I am new to this atlas stuff and have some questions.

1. Do i have to complete the nodes on every tier of maps?

2. If answer to 1 is no, so i can use Tier 1 maps to reach interest parts of the atlasmap and play there my higher tier maps?

3. Is the layout of the atlas map random for all and does it change over time so i have to complete it again?

Basics

1. Atlas has node maps, which each have distinct biomes determined by position on map and node from what I can tell. (https://poe2db.tw/Waystones#EndgameMaps can see all the base variations here)
2. To access nodes you have to use Waystones.
3. Way stones have tiers. https://poe2db.tw/Waystones. Base waystones only determine the level of the Atlas node maps you'll be entering. i.e. Tier 1 is level 65 through to Tier 16 is level 80.

Towers

1. A type of node map on Atlas.
2. You can access using a waystone.
3. By clearing the map, you'll be able to see more maps and insert precursor tablets.
4. By inserting precursor tablets you will irradiate surrounding maps.
5. By irradiating surrounding maps they'll gain mods, i.e. increased rarity found or additional waystones found and more if your lucky. These maps are better for loot generally. So a strategy people use is take shortest path to tower avoiding taking map nodes so they can irradiate as many maps as possible.
6. It is possible to have multiple irradiated maps if multiple towers close by if you put precursor in 2 tower and they both connected to same node map then that map will have additional buffs.

Waystones

1. You can turn these into magic and rare by using currency.
2. You can find them magic and rare.
3. The more buffs and higher the rarity, the harder the map tends to be so worth finding a balance. Rare is always good but harder to progress depending on your character and class, personally I have progressed to t10 only using magic to be safe and will do rare waystones once I get to t15 / t16 at that point I just want to beat tough stuff and get mad gear to farm for my alts.
4. I personally aim for waystones with experience gain mods on them, so I can level faster some have up to 40% and currently trade for 1 exalt on poe trade site.
5. Reforging bench, can take 3 of the same level waystones and give you +1 higher tier.
6. You can buy tiers from npc in game so keep checking back cheap gold or use poe site. Additionally if you have buffs on waystone they gives better chance of drop you can sustain how many maps you run for longer without having to buy.
7. Always look at the debuffs, if for example mobs deal more x elemental damage and you don't have the right level of resistance against that damage type I'd personally avoid this waystone.
8. Waystone quests you have to complete 10 of each tier type and it'll give you atlas node tree points 2 for every 10 completed. Super important to upgrade these to get more loots and rewards and find more waystones. In addition if your like me and rock up to maps at a higher level then 65 lol you can skip tier 1 maps and do ones more suited to your level to help gain xp. The quest still completes as long as your doing tiers higher than the one specified. I.e. for the tier 1 quest I was doing tier 3 / 4 maps and successfully able to complete.


Atlas Nodes Advanced

1. https://poe2db.tw/Waystones#MapLegends so many node types.
2. I personally like boss maps, delirium maps and irradiated maps for more loot gain.
3. The following are there too, I've not touched but have different end game challenges and experiences:-

The Realmgate
Copper Citadel
Iron Citadel
Stone Citadel
The Burning Monolith
Unique Maps ( I ran one, that gave crazy 200%+ xp but 0 loot, was great gave me half entire xp bar at level 75+. )

Your Questions

1. No
2. Yes, to get to more interesting map nodes I use lower level waystones or trashstones as I call them lol and save the better waystone and higher tier stuff for interesting map nodes i.e. irradiated, boss maps and will do, with the interesting stuff in point 3 about under atlas nodes advanced.
3. The atlas node is never ending infinite map, once you complete a node it is complete, if you fail a node you can run it again with a waystone but it'll have lost all its atlas node quirks i.e irradiation, boss, derilium etc.. it shouldn't change unless they reset and introduce new mechanics but I guess make more sense to add new mechanics to maps not done yet or parts not explored yet rather than hamper any exploration and irradiation with precursor tablets done by players.

Hope this helps. I'm still figuring it all out too, best way is to run and have fun, die and die some more unless your playing hardcore then don't die lol. Key is to also figure out why you die so you can look to build gear to counter towards it. Unfortunately best known builds have crazy trade prices so fine tuning late game can be bit of a grind to build better gear setups other option is to try your luck with crafting between crafting and getting loot on trade its an awesome grind life. Have fun.