Learn Farsi: بیایید شرایط جدید را خوب بسنجیم.

This is the standard Farsi structure for proposing an action. You use the imperative of the verb 'to come' — here biyâyid (plural/formal 'you come') — followed by your main action verb in the present subjunctive — here besanjim ('we evaluate').

Could I say biyâ instead of biyâyid in this sentence?

Yes, if you are talking to just one person informally. Biyâyid is used here because the speaker is addressing a group of people, or perhaps addressing one person formally.

The word for conditions is sharâyet. Where is the plural ending?

Sharâyet is an Arabic broken plural of the word shart (condition), so its internal structure changes rather than taking a regular Farsi plural suffix like -hâ. At this level, you will encounter many of these broken plurals for formal or abstract concepts.

As a refresher, why does the object marker râ come after the adjective jadid instead of the noun?

The specific direct object marker râ must follow the entire noun phrase, not just the head noun. Since the object being evaluated is the full phrase 'the new conditions' (sharâyet-e jadid), râ is placed at the very end of that phrase.

What is the infinitive of the main verb ?