The longest word that can be made is 7-letters: "MISCOPY"
If you repeat some of the letters you can make:
cosmisms, cyclicly, cyclosis, impolicy, lissomly, locoisms, lollipop, lollypop, piccolos, plimsoll, plimsols, psilosis, sciolism, scollops, simplism, slipslop, sloppily
There is no seven letter word that can be made from those letters. Words that can be made from the letters 'adtnpob' are:aadoadoptanandaptatatopbanbandbatbatonboaboatbonddabdodondotnabnapnonodnotoatonoptpapadpanpantpatpodpondpottabtadtantaptotoadtontop
There are 12 two letter arrangements of the letters in PARK.
Seven letter words that can be made from those letters are:amnesiapumpkin
'PROSCENIUM' itself is the only 10-letter word using those letters. There are several 8-letter words, but no other 10-letter ones.
The longest word that can be made using these letters is hydrolytic.
benesbinesjibesseine
laxity
Grandma
Eight letter word using the letters, naloeyianrgt: yearning. gyration. learning.
Seven letter words that can be made from those letters are shutter and stretch.
Five letter words that can be made from those letters are vodka and goads.
There is no seven letter English word that can be made from those letters. Words that can be made from the letters 'fcgraen' are:aaceacneacreageanangerarcarecafecagecancanecarcarecraneearearnerafacefanfangfarfarcefarefearfenfernfrancgeargracenacrenagnearraceragrageranrangrange