H-E-B
It looks like McCormick bought Schilling, and haven't used that brand since 2002, so any packets you could find of that exact seasoning would be quite old. I'm not sure if McCormick still uses the particular blend that used to be in the old packets, but they are the closest chance you have.
Yes. Vegetable oils are vegetable fat. If you want it in a solid form, you can buy vegetable shortening.
nowhere
There are many websites online that offer tuna casserole recipes. Some websites include FrugalityIsFree, AllRecipes, RecipeLion, Food, and Chow. Each website has their own variation on the tuna casserole recipe.
Amazon.com frequently sells a 5 pound container of the SPIKE seasoning for around $31.00 (plus shipping and handling).
You can buy it from the market or stores. There are a ton of stores that have them.
At your local grocery store.
You can buy the supreme-being gold pursuit jacket from ebay.
You can buy it from the TV, when you already have a kitchen. :)
You need to buy the seasoning set for the kitchen then it will be there
McCormick his company advertised , gave demonstrations and provided a repair and spare parts department . He also let customers buy on credits .
Broccoli, Corn, Eggplant, etc.