1. If you want me to give you my book and pencil, you have to tell me why you want them. (polite)
--> あなたは、あなたに私の本と鉛筆お上げるのというが欲 しければ、どうして欲しいか私に言わなくてはいけませ んよ。
(Anata wa, anata ni watashi no hon to enpitsu o ageru no to iuga hoshikereba, dōshitehoshī ka watashi ni iwanakute wa ikemasen yo.)
If you want the best possible wording for a situation where someone wants an explanation why they should lend their pen to someone politely, it probably wouldn't use the imperative (ie, I'd ask them for a reason, rather than demand one). I'd also drop all the pronouns; the speaker and listener know from the context who is who.
the grammar structure for wanting someone to do something is ~てほしい. 上げる is to raise, あげる is to give, 貸す is to lend. 理由を教える is to give (teach) a reason. を is the particle for direct object, お is NOT a particle.
grammatically, the second half of your sentence is understandable, but given the situation it doesn't seem like the best fit.
2. Does Su
zuki know that Ichirou went to her house yesterday? (casual)
--> 昨日
に鈴木さんは一郎さんが彼女の家を
行ったってゆう のが知るの?
(Kinō ni Suzuki-san wa Ichirō-san ga kanojo no ie o itta tte yū no ga shiru no?)
昨日 is never followed by に. 昨日、明日、今日、明後日、来週、来年are all relative times, and do not take a に particle. Specific times like 3時、明日十時半、去年の一月、1980三月24日、etc would take に
you could say 行ったのが知って(い)る/知って(い)た? or 行ったって知って(い)る/知って(い)た? to be more colloquial