How long does it take for a 3.5 lb chicken to defrost in the fridge? Also, how do I know if I have to remove anything inside?

When you get the chicken home from the butcher or market, unwrap it and remove the giblets. Rewrap them (liver separately - you can't use it for soup!) and freeze for later uses.
The "new" way is not to rinse the chicken, but I have been rinsing for the past 50 or so years, and I'm not stopping now. No one has ever gotten sick. But dry it thoroughly, inside and out! This is my favorite roast chicken recipe. I've been making it and teaching it for ever, and it always gets raves. https://food52.com/recipes/3401-perfect-roast-chicken There are lots of tips in that recipe, too.

This just came up on Food52 today : https://food52.com/recipes/64220-the-best-roast-chicken-with-pan-sauce-revisited#comments

It takes about 24 hour hours to defrost a chicken in the refrigerator. Chicken parts less time.

Salt & pep inside along with lemon and onion wedges and a few garlic cloves , maybe sprig of rosemary or thyme inside. I like an herby chicken so I put some herbs mixed with softened butter under the skin of the breasts and on top as well. dry the skin well before roasting so the skin crisps up. Once you make them yourself you wont want the store bought rotisserie ones any more. After I carve the chicken and make soup with the bones and carcass. Made these guys Sunday

Some tips:
Don't rinse the raw chicken in water (this spreads bacteria)
Look in the cavity, where you'll sometimes find a bag of innards...remove & can be used to make soup or gravy. Don't roast with them inside (I did this first time out...what a disaster!)
Some people truss or tie the bird, others cut it flat (called splayed or spatchcock).
Good to put a cut onion or lemon in the cavity when roasting...helps give flavor.
Use and make a good basic roast chicken recipe. There are many. Two favorites - by Michael Ruhlman, and Judy Rogers (late chef and restaurant owner in San Francisco).
Use the carcass of bones and bits of meat to make soup. Get every last bit of goodness out of that bird.

i know that when i take a cornish game hen from the freezer and put in fridge for 2 days, the ice in the cavity of the bird is still frozen. i usually run water inside until i can take the ice plug out the then cook as per recipe. i guess it depends on if there is water inside.