In regards to the first set of questions, swapping from look to mouse mode is how most FPS/RPGs work. Think Elder Scrolls series.
2. What does inn do? Without money, it doesn't even heal my health a bit! HOW RUDE!!! What a capitalism... And if I go to the inn, does the in-game time pass by? Does it have any effect on the game?
Inns are how you save & quit. With more money it will heal you a bit, but every class needs this differently. The priest, for example, doesn't even need the inn at all. He can save some coin that way. This game was released in 1997, started development in 95 I think. Many of the concepts you're seeing were very normal in era. Especially the cost of inns, and the cost going up. Many JRPGs only have one option, but other games have different. I know that in this year, Goemon's Great Adventure was released. This is a J-platformer and had tiers of inn usage. Much of it was to humorous effect, as you'll see with the inn description.
This game was probably more influenced from tabletop RPGs. And the latest 5th edition of Dungeons and Dragons has this kind of concept. You pay for inns and food at varying rates depending on how fancy they should be. In fact, you can purchase feasts which is a cool idea.
3. For all of the scrolls, only the experience scroll seems to have eternal effect on the character. Am I right?
Yes. This era was still experimenting on what magic should be. Most games wouldn't hand out any experience just for completing quests or reading scrolls. So a scroll of experience was a novel idea, and kind of new. Today's world of RPGs hand out XP as if it is some kind of tangible object that the person in front of you was holding. Here, have more XP. I know it tastes like toilet paper, but I swear it's good for you!
As someone growing up to these games, I find the new way of doing things pretty dumb. Why should I get 50 XP for handing a chicken to the tutorial narrator? Why can't I just go bash people in the face the good old fashioned way?
4. I can sometimes kill the archer with 2 hits or even 4 hits with iron long sword(6 dmg). Why?
The game has 2 randomized damage factors. The first is a percentile roll. When you attack you do (weapon damage + str bonus) + (random100% * weapon damage + str bonus). It then rolls another percentile. If that is less than your luck bonus, it doubles the damage. So an extremely lucky hit does 4 times regular damage. A very unlucky hit only does 1 times it.
6. Are wands usable for only one time?
No. They give arcane magic users access to mage spells. They use mana like a regular spell, but the big advantage is that they never fail to cast like a regular spell. Most classes can use the wands in limited situations due to their low mana.
I think the wands were kind of a bandaid to another game design principle. This is why I so heavily modded wands in my personal mod of the game.
7. I really wish I could swap weapons fast... Sometimes I really need to use sword and bow at the same time(at least it's much more fun!)
I kind of think that a primary/secondary system would be cool BUT it also breaks part of the game. At this stage of game development, the concept of inventories and inventory management was huge. Think Diablo and Diablo 2. Not having the ability to quickly swap weapons in diablo 1 was a purposefully designed feature.
In tabletop RPGs, swapping weapons is punished normally by sacrificing the player's turn. Although this is not the most realistic concept, it does favor the prepared. Being that games like this are way more heavily influenced by tabletop games mostly, making weapon switching have to be done manually enforces this time constraint. It also allows players to learn the fastest ways to solve the problem. I honestly love this about AA game. You can't just pop health potions to keep fighting. You have to come up with a better strategy. Holding health potions or weapons in your "free" mouse hand can speed things up. The Bactor/Mzbundifund videos describe this in the first video. Although he makes fun of it, it's a very charming feature.
Another thing about the feature, having a single spell prepared and a single item active defines how many characters work. The priest and paladin can have healing spells active while they fight. They have the fastest access to healing spells. All other characters have to turn to their inventory to heal. It's all about establishing a playstyle for the different classes.
