Which quests and missions from ME1 and 2 have an impact on ME3.

Intersting question in ME1 I'd say given these are main story quests you kinda have to do them anyway but it's moe rabout how you choose to handle them and that's Noveria and Virmire. Noveria is for the Rachni and Virmire for Kirrahe Wrex and whoever survives out of Ashley/Kaidan given that only one of them can.

The most obvious ones in ME2 are the loyalty missions because you're qsuaddies aren't giong t obe able to assist you in ME3 if they don't first survive ME2. The best way to make sure they do is to complete their loyalty quests.

Oher than the Asar iwritings and the license for Conrad's ME3 quest I don' t think so. As I think most just add XP from what I've gathered. Most of the things that affec twar assets and  story are only reall yfound in the main quests from what I can gather. A tleast in all the playthrough's I've done.

For the Conrad quest in ME3, you also need to complete Gavin Hossle quest on Feros. 

If for you Tali's pilgrimage is part of the main story (considering "dialogue differences" if you did not give her the data and no further mentioning about that) there are some other such quests from ME1 since they change dialogues, you can meet some people depending on your choices, get some more letters with different information (Cerberus/Asari Diplomat/Rita's sister etc).

No great impact on anything at all (as with Tali's quest in ME1), but, again, as with Tali's quest - more connections and reminders for you that you actually played ME1 and finished not only plot quests.

You have more connection with Conrad actually (also depending what you do to him in ME2), but still, some changes you will have, story, not war assets (war assets may change if you prefer right hook and not in the mood to save untrained girl working under cover).

Although, such minor changes are more interesting if you can notice them yourself when during the 1st PT you did not do those quests (or did, but had one outcome, e.g. did not help Jenna), and during the 2nd-Xx PTs you did those quests and saw the diffrence.

With ME2 it is very easy and difficult at the same time - there are different outcomes depending on LMs, choices etc. Impact on the story and war assets as well, but not that great. Would say it's more about story.

Thank you very much for the information Sonya and dmc1001.

Thank you very much for the link to your thread.