Recently, one of my friends asked me about a lot of things in Islam. Alhamdullillah, I am happy to answer all the questions. Insha'allah, I pray Allah guide us to the right path. A'meen  
The first question is: Where is hell and heaven...if heaven is in the sky why don´t we crash our planes into it?
     That is not permissible is Islam because and it is not possible for a human brain to imagine something which it hasn't experienced, as the      Prophet  (peace and blessings of Allaah be upon him) told us that Allah said, describing Paradise: “I have prepared for My righteous servants      that which no eye has seen, no ear has heard, and it has not crossed the      mind of man. Recite, if you wish:
     ‘No person knows what is kept hidden for them of joy’ [al-Sajdah 32:17 – interpretation of the meaning].”  (Narrated by al-Bukhaari, 3244; Muslim, 3824).
     This drawing may lead to belittling of the delights of Paradise;  the descriptions narrated in the Qur’aan and Sunnah are sufficient, as  the Prophet  (peace and blessings of Allaah be upon him)      explained to his companions. And Allah knows best.
Resurrection and the Day of Judgement
A central doctrine of the Qur'an is the 
Last Day, on which the world will be destroyed and Allah will raise all people and 
jinn from the dead to be judged. The Last Day is also called the Day of Standing Up, Day of  Separation, Day of Reckoning, Day of Awakening, Day of Judgment, The  Encompassing Day or The Hour. 
Until the Day of Judgment, deceased souls remain in their graves  awaiting the resurrection. However, they begin to feel immediately a  taste of their destiny to come. Those bound for hell will suffer in  their graves, while those bound for heaven will be in peace until that  time.The resurrection that will take place on the Last Day is  physical, and is explained by suggesting that God will re-create the  decayed body (17:100: "Could they not see that God who created the  heavens and the earth is able to create the like of them"?).
On the Last Day, resurrected humans and 
jinn will be  judged by Allah according to their deeds. One's eternal destination  depends on balance of good to bad deeds in life. They are either granted  admission to 
Paradise, where they will enjoy spiritual and physical pleasures forever, or condemned to 
Hell  to suffer spiritual and physical torment for eternity. The day of  judgment is described as passing over Hell on a narrow bridge in order  to enter Paradise. Those who fall, weighted by their bad deeds, will  remain in Hell forever. 
The Qur'an specifies two exceptions to this general rule: 
- Warriors who die fighting in the cause of God are ushered immediately to God's presence (2:159 and 3:169); and 
 
- "Enemies of Islam" are sentenced immediately to Hell upon death.
 
 
Paradise
"O soul who is at rest, return to thy Lord,  well-pleased with Him, well-pleasing Him. So enter among My servants,  and enter My garden." (89:27-30) 
Paradise (
firdaws), also called "The Garden" (
Janna),  is a place of physical and spiritual pleasure, with lofty mansions  (39:20, 29:58-59), delicious food and drink (52:22, 52:19, 38:51), and  virgin companions called 
houris (56:17-19, 52:24-25, 76:19,  56:35-38, 37:48-49, 38:52-54, 44:51-56, 52:20-21). There are seven  heavens (17:46, 23:88, 41:11, 65:12).
 
Hell
Hell, or 
Jahannam (Greek 
gehenna), is mentioned frequently in the Qur'an and the Sunnah (What our profit did?)  using a variety of imagery. It has seven doors  (Qur'an 39:71; 15:43)  leading to a fiery crater of various levels, the lowest of which  contains the tree Zaqqum and a cauldron of boiling pitch. The level of  hell depends on the degree of offenses. Suffering is both physical and  spiritual. 
Being a Muslim does not keep one out of Hell, but it is not clear whether Muslims remain in Hell forever. Non-Muslims (
kafir), however, will be punished eternally. A Muslim author on IslamOnline.net explains it this way:
"Ultimately, God will remove from Hell those believers  whose sins were not forgiven nor atoned for by good deeds in their  lifetimes, and they will then enter Paradise. The remaining inhabitants  of Hell will stay there eternally." (Islam Online)
Other Muslim commentators, noting that Allah can rescue people  from hell as he chooses, and that he is merciful and compassionate, have  hypothesized that eventually hell will be empty. Alternatively, Hell  can be seen as a place of progress where souls are instructed until they  are fit to go to heaven. Although, this is an argument of a complicated discussion among Islamic scholars.
There is a good post about Heaven/ Hell @ http://www.answering-christianity.com/heaven_hell.htm
Another good post is @ http://www.online-literature.com/forums/showthread.php?t=27175
Allah guide us to the right path... Ameen