Variable Colums In Stacked Table

Hello, and thanks for taking the time to read this.

NOOB question:

In dealing with, say, shirts -- I have a DB that serves as a template for several customers. Each customer may have different ranges of sizes (one may have S,M,L and the other might also have XL,XXL). So the CATALOG table is:

CREATE TABLE [dbo].[T_Catalog](
[StlyeID] [int]
) ON [PRIMARY]
with data:
1
2


the SIZES table (filled in by the customer with all the size ranges they carry) is:

CREATE TABLE [dbo].[T_Sizes](
[SizeID] [int],
[SizeName] [nchar](10)
) ON [PRIMARY]
with data:

1,Small
2,Medium
3,Large
4,Xtra-Large

and the AVAILSIZES table would be:

CREATE TABLE [dbo].[T_AvailSizes](
[StyleID] [int],
[SizeID] [int]
) ON [PRIMARY]

1,1
1,2
1,3
2,1
2,3
2,4

Basically, then, we know that:

style 1 comes in Small, Medium, and Large
style 2 xomes in Small, Large, and Xtra large

WE know that, but getting SQL to tell us that is a major PIA!!

Now,

SELECT
t_Catalog.StyleId, t_AvailSizes.SizeID
FROM
t_Catalog
INNER JOIN t_AvailSizes ON
t_Catalog.StyleId = t_AvailSizes.StyleId

will give me a nice list of each item number with a separate row for each size number.

My questions are:

How do I get the size NAMES?

How would I get all of the sizes into a single row, so that there is a single row for each catalog StyleID (that's all I ever wanted to begin with)?

Is this the right way of doing this?

In reality I have about six columns that can contain multiple and variable items like this, and when trying to even think about resolving it all into a single record my brain tries desparately to crawl out my left ear.

Thanks for any help and information you can provide.