I am a revert and I have some questions regarding Ahaadith

Q: I am a revert to Islam, and I'm still learning..however I have come across some hadith, that contradict the teachings and character of our beloved Nabi (Sallallahu Alayhi Wasallam)..one example, the Prophet (Sallallahu Alayhi Wasallam) told his son to divorce his wife so that he (saw) could marry her for himself..another example is that he ordered the killing of 100's of Jewish men because they didn't accept Islam and allowed his men to rape the women of those slain men..my question is: Are all hadith true and authentic, and if not, which hadith should we follow?

Visiting the holy lands

Q: I am very despondent at the moment as I feel that I will never be able to visit Makkah and Madinah because I am not earning and also do not have financial means to go. I feel that I will never get a chance to go. Please make dua for me to go and also advise me on how I can change my thinking and be hopeful in the mercy of Allah.

Using a black pen

Q: “On one occasion Shaykh Zulfiqar Naqshbandi Saheb (db), while on a journey to Zambia, requested a pen from one of his Khulafa. The Khalifa took out a Blue pen from his pocket and presented it to the Shaikh. On seeing the pen, the Shaikh said, “Subhanallah Mawlana saheb, Are you not aware of the ink colour which is Sunnah?” At this the Respected Khalifah said, that he was set aback by this, and it put his mind and heart to distress. He began thinking, what is the Sunnah ink colour? Then the Shaikh mentioned that “Haven’t you read, the colour of Ink that Nabi (Sallallahu Alayhi Wasallam) used on the occasion when he wrote letters to Kaiser and Kisra?” And then, the Khalifa remembered that, Nabi (Sallallahu Alayhi Wasallam) had used black ink.” 

Mufti Saheb, in light of the above, will I be rewarded for using a black pen  instead of another colour if my intention is to gain the Pleasure of Allah Ta’ala by following the Sunnah?

I have no problem with Hazrat Shaykh Zulfiqar Ahmed Naqshbandi (db), it is just that this the first time I became aware of this particular Sunnah. In addition, I thought Nabi Muhammad (Sallallahu 'Alaihi Wa Sallam) was illiterate and thus unable to write. Therefore, I am uncertain. Please advise.

Spots on one's underwear

Q: When I get up in the morning, I see some little spots on my underwear. I am unable to decide if these are the spots of mani or any other liquid.

But I can give some detail about I experiences related to this problem:

  1. I see these spots daily.
  2. I feel nothing all night and no wet dream.
  3. When I wash my private part, it seems like something oily is applied on the top of it.
  4. These spots are white.

​Please tell me if I have to make ghusal daily or just change my underwear after cleaning my private part?