When Allah mentions the state of those who are doomed, He follows that by mentioning the blessed who believed in Allah and believed what His Messengers brought, and did the righteous deeds that they were commanded to do.

means, from beneath its rooms and dwellings. Fir'awn said:

{they will be adorned} means, with jewelry.

Allah says elsewhere:

{and pearls and their garments therein will be of silk} (22:23).
This is explained in more detail here, where Allah says:

Sundus refers to a fine garment, like a shirt and the like, and Istabraq is thick and shiny velvet.

The word Muttaki'in implies lying down, or it was said that it means sitting with one's legs crossed, which is closer to the meaning here. In a Sahih Hadith, the Prophet said:

"As for me, I do not eat sitting with legs crossed (Muttaki'an)".

Ara'ik is the plural of Arikah, which is a bed under a canopy. And Allah knows best.

means, how blessed is Paradise as a reward for their good deeds. And what an excellent Murtafaq means, and how good a place to dwell and rest and stay. Previously, Allah had said of Hell,

{Terrible is the drink, and an evil place of rest (Murtafaq)!} [18:29].