Yes, 窶忱窶破窶愿コ窶堙俄?堙?ツ食窶堙冷?堙懌?堋オ窶堋スツ。is OK. (Since the sentence is not strictly formal, "ni" is not always necessary. If you're a stickler with grammar, use "ni" by all means. )
窶忱窶破窶愿コ窶堙俄?堙? will certainly be understood, but it's not natural Japanese. I'd say:
窶忱窶破窶愿コツ(窶堙可)窶堙?窶堙仰。
窶忱窶破窶堙?窶堙仰。ツ(窶愿コ can be omitted when referring to the days of the week, such as ナ椎ス窶破ツ、窶ーテ寂?破)
But in formal speech, use 窶忱窶破窶愿コ窶堙俄?堙?ツ食窶堙冷?堙懌?堋オ窶堋スツ。