I missed one blue meteorite from Haren Brogg in chapter 1, just wondering if meteorite ore is important, I checked the wiki and find out meteorite ore is in limited amount. Should I replay from chapter 1 or just keep going? Thanks.

It is important if you wanna modify the sword, first time I palyed, I used unmodified swords...

You can probably just keep going. You'll find more meteorite ore as you play. I reforged my sword a few times throughout the game but it's not essential and you'll probably find better meteorite ore later anyway.

And better steel swords; in Chapter 2, once you've levelled up enough to fight wyverns, you can find Harvall. Compare its stats to http://witcher.wikia.com/wiki/Meteorite_swords_in_The_Witcher and decide what best suits your needs.

No its not so important because you will be able to get unic swords which are better then swords made with ore. Even if you want to make a sword with ore my personal suggestion to you is to make a sword from 3 red ores this is the best combination IMO.

If 'unic' = runic, those are silver swords, not steel.

http://witcher.wikia.com/wiki/Rune_swords

I think "unic" was meant to mean "unique", i.e. certain steel swords that can be found in the game that have very nice stats.

You do not need that. By the time you will have a meteorite sword crafted, you will have found swords like Harvall. And even if you haven't, oils and potions work well. Meteorite swords are very good, but nothing spectacular, though, especially if you compare them to special weapons, or (secret) loot.

Best one of them is the 3 yellow ore one, for steel, and 3 sun runes one, for silver. They both become outdated and useless in comparison to Mahakaman Rune Sihil and Aerondight, respectively.

You should craft the silver one, it is useful for Act 4 and its boss. And in act 2, it would be nice having a steel meteorite one forged. But you shouldn't stress yourself about... Try shopping from dwarven blacksmith and armor blacksmith, before the quests that make one of them unavailable. Thaler also has some.