Inmates can get commissary once per week provided they have money on their account. Sometimes, the order is filled same-day, others it 1-2 day from submittal of the order form. Once the inmate goes through orientation, they can make a phone list and begin calling (again, they'll need money on their books).

Once per week

Yes they do, but you will have to place money on the inmate's acount and the inmate will have to select and buy their own items.

It depends on where they are incarcerated, all commissary lists are different, but similar in the range of available products. Inmates may buy stamps and writing supplies for mailing letters, they can buy snacks and candy or savory foods like tuna, mackerel, salmon, chicken, soups (add hot water), toiletries, grooming aids, dental and hygiene products, sweatshirts and sneakers and various sundries. I was in county, private and federal prison and by far the most important purchase are your headphones

Not normally - usually they are bought at the commissary. But since we do not know the prison or jail your inmate is located in, we'd advise you to call the unit secretary at the facility to get their rules on bringing things.

yes, once per week as long as there is money in their account

Inmates can buy longjohns-type shirts or sweatshirts at the commissary.

SCDC sponsors four (4) Inmate Package Programs yearly whereby inmate's family/friends may order various package combinations from Access Securepak for shipment to Leath Correctional. The packages contain a wide variety of snacks, candy, and seafood.  LIMITS: $200 limit applies to food and snacks only Each food item (excluding Ramen) has maximum purchase limit of 12 Ramen Noodles are limited to (4) 24 packs Maximum of 3 hygiene products Multiple orders allowed, but not to exceed the dollar

It depends on the facility. In federal, the amount is $320 per month ($370 in November and December) on commissary items.  This does not include over-the-counter medications, copy cards, or postage stamps. In state prison, the weekly amounts range from $40-60. In the county jails it is about $75 per week. The private prisons like CoreCivic or GEO also allow $75 per week. 

Commissary is once a week. It typically takes one week before the newer inmates can get commissary. But it is more related to the "day of the week they are designated", for instance if they come into the institution on a Wednesday and the commissary day for him is on Tuesday, then he'll be able to go the next Tuesday. Also, money in their account must be there in advance.