Paradise

Allah (SWT) will bring the pious believers in the Paradise in the best shape. Even old aged will be in the form of youth. Whatever they wish will be granted to them in the Paradise (Sura 43, Verse 71). No one in Paradise will wish to be non-human in form, because Allah will remove from them every bad thought (And We shall remove them every bad feeling) Sura Al-Hijr, verse 47.

Wassalam.

We don't have details whether Satan was able to see Hellfire or not but we know that he disobeyed Allah when Allah ordered him to prostrate to Adam. Satan was told that he and all those who will follow him will be in Hellfire (Sura 15, verses 42 and 43).

Wassalam.

She will be in Paradise with the best of them if both of them were in Paradise.

Wassalam.

According to many narrations, certain animals (either mentioned in Quran or authentic Hadeeths) will enter the Paradise like:

1.The she-camel of prophet Salih (AS) which was killed by the disbelievers, mentioned in Quran Sura 91, Verse 13.

2. The calf of Ibraheem (AS). (Sura 51, Verse 26.)

3. The ram of Esmaeel (AS). (Sura 37, verse 107).

4. The cow of Musa (AS. (Sura 2, Verse 67).

5. The whale of Younus  (AS). (Sura 37, verse 142).

6. The donkey of al-Ozair (AS). (2:259).

7. The ant of Sulaiman (AS). (Sura 27, verse 18).

8. The hoopoe of Bilqees. ( Sura 27, verse 20).

9. The dog of the people of the Cave. (Sura 18, verse 18.

10. The She-camel of the Prophet Muhammad (AS).

Wassalam.

No doubt at all that Imam Hasan (AS) and Imam Husain (AS) are the two masters of all the youth in Paradise. This fact has been mentioned in many  Hadeeths in Sunni and Shia books. The Hadeeth states also : Their father is better than them وأبوهما خير منهما. Al-Mustadrak ala al-Saheehain by al-Haakim al-Nisabori , V.3, P.182.

All believers in the Paradise will be young even if they dies in old age. There will be no old age in Paradise. The masters of all in the Paradise will be the Prophet Muhammad (SAWA) being the Best of all creatures, then Imam Ali (As) as it is mentioned in the Hadeeth, then Imam Hasan (AS) and Imam Husain (AS).

Wassalam.

No bad in the Paradise at all. Allah says in Quran about people in Paradise :ونزعنا ما في صدورهم من غِلّ (We shall remove from their chests all the hatred and make them real brothers). Sura 15, verse 47.

No one in Paradise thinks negatively nor has negative feelings whatsoever. No one will wish to do any wrong or even think to do any wrong as Allah has granted them the ability to see the right and wrong clearly so no one will ever want to do or think about doing wrong.

'Wassalam.

There is no disbelieving child even if his parents were disbelievers. Children are born on the distinct (Fitra) which has dasics of faith. No one will be punished by a Allah, The Glorious, before knowing and insisting on denying the truth after knowing the truth. Children who die in their childhood will be given on the Day of resurrection full option to know the truth then decide. If they accept the truth, they will be in the Paradise.

Wassalam.

The reward of the believers who do good does not depend on the quantity but the quality of worship. Quality of worship depends on the degree of sincerity and dedication to Allah (SWT). Woman during menstruation gets reward for every good deed she does and gets also compensation for the suffering of menstruation. That will make her reward not less that the reward of pious men who do good. There is no question of any discrimination between man and woman in front of Allah (SWT) who created both of them and granted them equal chances and help to do good. 
'Wassalam.