for your first point about projectiles:
Roy has great vertical movement. hes got a quick fall speed, quick FF speed, and a short full hop, shorts hop, and double jump. while the short jumps do have disadvantages in other situations (like attempting to be mobile on places like dreamland), they tend to mean that roy can perform pretty well against projectiles. since he can move very quickly up and down, he can navigate projectile mazes like links or marios pretty well. he also has great space coverage options like fair, ftilt, jab, and DED that can swat out or at least clank with projectiles. since your grab range is so large, and you have a relatively good wavedash, shielding is a pretty viable option as well. you can go for the powershield reflect, and if you dont hit it, then you at least have a good grab range to command space and help defend against approaches, and a good escape option. overall, you should try to understand what distance each opponents projectile is safe in. in other words, theres a certain distance away from them that you can be where if they fire a projectile, you can punish the endlag. try and predict their projectiles, and threaten that range very tightly, until you can get something off that will give you a hit on them.
for your second point about his grabs:
roys grabs are definitely good. in fact, im pretty sure theyre identical to marths outside of uthrow, where roys has more KB overall. marth gets more chain grabs out of fthrow because of his greater grab range and dash speed; however, this doesnt mean roy doesnt get meaningful conversions out of his grabs. in fact, because of roys dtilt, he is far likelier to get good set ups for combos out of tech chases from his throws. ill detail the basics of his 4 throws:
uthrow: great for chain grabs on FFers. can kill characters at very high percents as a last ditch option. the higher BKB than marths means that chain grabs start eariler but also end earlier. this doesnt really affect the overall reward roy gets compared to marth, since roy generally has more effective uair strings, and can lead straight into regrabs, fsmashes, or bairs from those. marth doesnt get that potential for a kill set up as easily.
bthrow: positional throw. you wont get combos off this, but it will put them offstage.
fthrow: chain grabs a bit at low low percents. sets up for tech chases (DI away) or direct follow ups if they dont DI for a tech, or are too floaty to get a tech. direct follow ups can result in ftilts, fairs, DACUSs, dtilts, fsmashes, dash attacks, or regrabs depending on character, DI, and percent. These are possible because fthrow and dthrow create a DI mix up situation. if you DI to avoid follow ups on fthrow, then a dthrow will cause you to DI in, which allows for a direct follow up, and vice versa. ftilts from a fthrow are almost always guarenteed at relevant percents. tech chases from a fthrow can result in a plethora of things, most notably a dtilt. dtilt works great during tech chases because of its range, great combo potential, and extremely low endlag, that allows you to effectively cover and punish multiple roll options. overall, fthrow is gernrally your best throw for follow ups and tech chases.
dthrow: like stated before, dthrow creates a DI mixup when used in conjunction with fthrow. both of these throws look nearly identical, and are very quick, so its quite hard to react for proper DI, making it a guessing game. if you cause your opponent to DI on a dthrow, you can yield fsmashes, bairs, and neutral bs for kills. DI away will cause tech chases, but the higher end lag on dthrow makes fthrow the superior tech chase throw. its still very effective for tech chases nonetheless unless you have a heavy opponent (meaning the animation is longer).
overall, roy has a very effective throw game. he doesnt have kill combos straight from throws like mario does, but he gets plenty of kill set ups and conversions from the throws.
